Magnet removal and replacement apparatus and methods for use with cochlear implants

ABSTRACT

Apparatus and methods for installing a MR-compatible magnet apparatus into a cochlear implant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/543,798, filed Aug. 10, 2017, which is incorporated herein byreference. This application also claims the benefit of U.S. ProvisionalApplication No. 62/560,282, filed Sep. 19, 2017, which is incorporatedherein by reference.

BACKGROUND 1. Field

The present disclosure relates generally to the implantable portion ofimplantable cochlear stimulation (or “ICS”) systems.

2. Description of the Related Art

ICS systems are used to help the profoundly deaf perceive a sensation ofsound by directly exciting the intact auditory nerve with controlledimpulses of electrical current. Ambient sound pressure waves are pickedup by an externally worn microphone and converted to electrical signals.The electrical signals, in turn, are processed by a sound processor,converted to a pulse sequence having varying pulse widths, rates and/oramplitudes, and transmitted to an implanted receiver circuit of the ICSsystem. The implanted receiver circuit is connected to an implantableelectrode array that has been inserted into the cochlea of the innerear, and electrical stimulation current is applied to varying electrodecombinations to create a perception of sound. The electrode array may,alternatively, be directly inserted into the cochlear nerve withoutresiding in the cochlea. A representative ICS system is disclosed inU.S. Pat. No. 5,824,022, which is entitled “Cochlear Stimulation SystemEmploying Behind-The-Ear Sound processor With Remote Control” andincorporated herein by reference in its entirety. Examples ofcommercially available ICS sound processors include, but are not limitedto, the Harmony™ BTE sound processor, the Naida™ CI Q Series soundprocessor and the Neptune™ body worn sound processor, which areavailable from Advanced Bionics.

As alluded to above, some ICS systems include an implantable cochlearstimulator (or “cochlear implant”), a sound processor unit (e.g., a bodyworn processor or behind-the-ear processor), and a microphone that ispart of, or is in communication with, the sound processor unit. Thecochlear implant communicates with the sound processor unit and, someICS systems include a headpiece that is in communication with both thesound processor unit and the cochlear implant. The headpiececommunicates with the cochlear implant by way of a transmitter (e.g., anantenna) on the headpiece and a receiver (e.g., an antenna) on theimplant. Optimum communication is achieved when the transmitter and thereceiver are aligned with one another. To that end, the headpiece andthe cochlear implant may include respective positioning magnets that areattracted to one another, and that maintain the position of theheadpiece transmitter over the implant receiver. The implant magnet may,for example, be located within a pocket in the cochlear implant housing.

One example of a conventional cochlear implant (or “implantable cochlearstimulator”) is the cochlear implant 10 illustrated in FIGS. 1 and 2.The cochlear implant 10 includes a flexible housing 12 formed from asilicone elastomer or other suitable material, a processor assembly 14,a cochlear lead 16, and an antenna 18 that may be used to receive dataand power by way of an external antenna that is associated with, forexample, a sound processor unit. The cochlear lead 16 may include aflexible body 20, an electrode array 22 at one end of the flexible body,and a plurality of wires (not shown) that extend through the flexiblebody from the electrodes 24 (e.g., platinum electrodes) in the array 22to the other end of the flexible body. The antenna 18 is located withinan antenna portion 26 of the housing 12. A cylindrical magnet 28, withnorth and south magnetic dipoles that are aligned in the axialdirection, is located within a pocket 30 in the housing antenna portion26. The magnet 28 is used to maintain the position of a headpiecetransmitter over the antenna 18, and includes magnetic material 32 and ahermetically sealed case 34. The exemplary processor assembly 14, whichis connected to the electrode array 22 and antenna 18, includes aprinted circuit board 36 with a stimulation processor 38 that is locatedwithin a hermetically sealed case 40. The stimulation processor 38converts the stimulation data into stimulation signals that stimulatethe electrodes 24 of the electrode array 22.

There are some instances where it is necessary to remove the magnet froma conventional cochlear implant, and then reinsert the magnet, in situ,i.e., with the cochlear implant accessed by way of an incision in theskin. To that end, the magnet 28 can be inserted into, and removed from,the housing pocket 30 by way of a magnet aperture 42 that extendsthrough the housing top wall 44 (which defines the top surface of thehousing). The magnet 28 is larger than the magnet aperture 42, i.e., theouter perimeter of the magnet is greater than the perimeter of themagnet aperture. The portion of the top wall 44 between the aperture 42and the outer edge of the magnet forms a retainer 46 that, absentdeformation of the aperture and retainer, prevents the magnet fromcoming out of the housing 12. During installation and removal, theaperture 42 and retainer 46 are stretched or otherwise deformed so thatthe magnet 28 can pass through the aperture.

The present inventors have determined that conventional cochlearimplants are susceptible to improvement. For example, removal andreinsertion of the implant magnet by way of the aperture may be requiredbecause some conventional cochlear implants are not compatible withmagnetic resonance imaging (“MRI”) systems. As illustrated in FIG. 3,the implant magnet 28 produces a magnetic field M in a direction that isperpendicular to the patient's skin and parallel to the axis A. Thismagnetic field direction is not aligned with, and may be perpendicularto (as shown), the direction of the MRI magnetic field B. Themisalignment of the interacting magnetic fields M and B is problematicfor a number of reasons. The dominant MRI magnetic field B (typically1.5 Tesla or more) may generate a significant amount of torque T on themagnet 28. The torque T may be sufficient to deform the retainer 46,dislodge the magnet 28 from the pocket 30, and cause reorientation ofthe magnet. Reorientation of the magnet 28 can place significant stresson the dermis (or “skin”), which cause significant pain. In someinstances, the magnet 28 may rotate 180 degrees, thereby reversing theN-S orientation of the magnet.

As alluded to above, magnet rotation may be avoided by surgicallyremoving the positioning magnet prior to the MRI procedure and thenreinserting the magnet after the procedure. A wide variety of removablepositioning magnets, and removable positioning magnet systems, have beenemployed in conventional cochlear implants. The manner in which themagnet is removed from the magnet pocket will depend upon the type ofmagnet or magnet system. For example, some positioning magnets simplyinclude magnetic material that is hermetically sealed within abiocompatible case (such as a titanium case) or magnetic material thatis sealed within a biocompatible coating, and may be removed from themagnet pocket in the manner described above. Positioning magnet 28 isone example of a positioning magnet that includes magnet material withina titanium case.

Other positioning magnets are part of systems that include structureswhich are capable preventing magnet reorientation in relatively lowstrength MRI magnetic fields, while permitting removal if necessary. Forexample, U.S. Pat. No. 9,352,149 discloses a system that includes aretainer which surrounds the magnet pocket and is embedded within theimplant housing and a magnet case that may be secured to the retainerthrough the use of threads (or other mechanical interconnects) on theretainer and magnet case. U.S. Pat. Pub. No. 2016/0144170 discloses anembedded retainer (referred to as a “mounting”) and a magnet thatinclude mechanical interconnects that allow the magnet to be rotatedinto engagement with the retainer, as well as other releasablemechanical connectors that secure the magnet within the magnet pocketand allow removal of the magnet as necessary. Other systems, such asthose disclosed in U.S. Pat. No. 8,340,774, include a retainer in whichthe magnet is located. The retainer (in which the magnet is located) maybe inserted into an opening in the elastomeric housing of the associatedcochlear implant, and also removed from the housing if necessary.References herein to “positioning magnets” include all such removablepositioning magnets as well as the removable magnetic portions of allsuch systems.

The present inventors have determined that removal and reinsertion canbe problematic because some patients will have many MRI proceduresduring their lifetimes, and repeated surgeries can result in skinnecrosis at the implant site. More recently, implant magnet apparatusthat are compatible with MRI systems have been developed. Examples ofMRI-compatible magnet apparatus are disclosed in PCT Pat. Pub. No.2016/190886 and PCT Pat. Pub. No. 2017/105604, which are incorporatedherein by reference in their entireties. The present inventors havedetermined that although MRI-compatible magnet apparatus are an advancein the art, such magnet apparatus will not physically fit into themagnet pocket of many older cochlear implants that are already implantedin patients, thereby preventing the replacement of a conventional magnetwith a MRI-compatible magnet apparatus.

Other proposed techniques for avoiding the magnet rotation associatedwith MRI procedures involve using one or more bone screws to anchor themagnet to the skull. The present inventors have determined that theseconventional techniques are susceptible to improvement. For example, thetorque on the magnet generated by the dominant MRI magnetic field B cancause trauma to the bone tissue and discomfort to the patient. Thetorque may also break or demagnetize the magnet. Moreover, bone screwstend to become permanently integrated into the bone, which can beproblematic should removal of the cochlear implant become necessary.Here, the bone screws must be drilled out of the bone and, when theremoved implant (or a replacement implant) is subsequently implanted,the new bone screws must be offset from the prior bone screw locations.As a result, the cochlear implant, including the lead that carries theelectrode array, must be repositioned.

Accordingly, the present inventors have determined that it would bedesirable to provide apparatus and methods which facilitate thereplacement of a conventional implant magnet with an MRI-compatiblemagnet apparatus, even in those instances where the MRI-compatiblemagnet apparatus will not physically fit into the magnet pocket of theassociated cochlear implant. The present inventors have also determinedit would be desirable to employ bone screws (or other anchors) in such amanner that the presence of a dominant MRI magnetic field will notresult in trauma to the bone or damage to the magnet, and that willfacilitate replacement of the cochlear implant without removal of anassociated MRI-compatible magnet apparatus.

SUMMARY

A method, for use with a cochlear implant, includes the steps ofremoving a portion of the resilient material from the cochlear implanthousing and replacing the magnet with an MRI-compatible magnet apparatusthat is larger than the magnet within the antenna pocket, or with amagnet that is larger than the magnet within the antenna pocket.

A magnet apparatus insert, for use with a cochlear implant, includes ahousing portion replacement having a magnet housing formed from aresilient elastomer and configured to fit within an aperture in theantenna portion of the cochlear implant housing, and an MRI-compatiblemagnet apparatus embedded at least partially within the magnet housing.

A cochlear implant with a cochlear implant housing, formed from aresilient elastomer, including an antenna portion and an aperture withinthe antenna portion that extends at least partially through the cochlearimplant housing, an antenna within the antenna portion, a stimulationprocessor within the cochlear implant housing operably connected to theantenna and to the cochlear lead, and a magnet apparatus insert at leastpartially within the aperture.

A cutting tool positioner, for use with a cochlear implant, includes acentering post including a handle and an anchor, operably connected tothe handle, configured to fit into the cochlear implant magnet pocket,and a tool guide, rotatably mounted on the centering post, including aslot configured to receive a cutting tool blade.

A center punch, for use with a cochlear implant, includes a centeringpost including a handle and an anchor, operably connected to the handle,configured to fit into the cochlear implant magnet pocket, and a cutter,mounted on the centering post and longitudinally movable relative to thecentering post, including a blade with an overall circular shape.

A pocket enlargement tool, for use with a cochlear implant, includes ahandle and means, operably connected to the handle, for enlarging themagnet pocket by shaving material off of the cochlear implant housingfrom within the magnet pocket as the handle is rotated.

A kit, for use with an implanted cochlear implant, includes anMRI-compatible magnet apparatus and one or more tools configured toremove a portion of the resilient material from the cochlear implanthousing.

A coring and removal tool for use with a cochlear implant includes acentering template having an abutment, and a cutter, including a bladewith an overall circular shape and an inner diameter that is greaterthan the diameter of the cochlear implant magnet pocket and less thanthe diameter of the cochlear implant antenna, that is movable relativeto the centering template. The centering template and the cuttercochlear implant operably associated with one another such that thecutter blade will be centered relative to the magnet when the abutmentengages the antenna portion.

There are a number of advantages associated with such apparatus andmethods. For example, the present apparatus and methods facilitate thereplacement of a conventional implant magnet with an MRI-compatiblemagnet apparatus in those instances where the MRI-compatible magnetapparatus will not physically fit into the magnet pocket of theassociated cochlear implant.

A method, for use with a cochlear implant, includes the steps ofremoving a portion of the resilient material from the cochlear implanthousing and replacing the cochlear implant magnet with an MRI-compatiblemagnet apparatus, and anchoring the MRI-compatible magnet apparatus tobone.

A magnet apparatus, for use with a cochlear implant or other implantablemedical device, includes a case, at least one magnetic element withinthe case that is rotatable relative to the case, and a bone anchorassociated with the case that is configured to anchor the case to bone.The present inventions also include cochlear implants with such a magnetapparatus.

There are a number of advantages associated with such apparatus andmethods. For example, the present apparatus and methods facilitate thereplacement of a conventional implant magnet with an MRI-compatiblemagnet apparatus. The present inventions also allow bone screws (orother anchors) to be employed in such a manner that the presence of adominant MRI magnetic field will not result in trauma to the bone ordamage to the magnet.

The above described and many other features of the present inventionswill become apparent as the inventions become better understood byreference to the following detailed description when considered inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed descriptions of the exemplary embodiments will be made withreference to the accompanying drawings.

FIG. 1 is a top view of a conventional cochlear implant.

FIG. 2 is a section view taken along line 2-2 in FIG. 1.

FIG. 3 is a partial section view showing the conventional cochlearimplant as an MRI magnetic field is being applied.

FIG. 4 is a partial section view of an aspect of a cochlear implantmodification process in accordance with one embodiment of a presentinvention.

FIG. 5 is a section view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 6 is a top view the aspect of the cochlear implant modificationprocess illustrated in FIG. 5.

FIG. 7A is a top view of a magnet apparatus insert in accordance withone embodiment of a present invention.

FIG. 7B is a side view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 8 is a partial section view of a modified cochlear implant inaccordance with one embodiment of a present invention.

FIG. 9 is a section view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 10 is a side view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 11 is a partial section view of a modified cochlear implant inaccordance with one embodiment of a present invention.

FIG. 12 is a section view of an aspect of a cochlear implantmodification process in accordance with one embodiment of a presentinvention.

FIG. 13 is a partial section view of a modified cochlear implant inaccordance with one embodiment of a present invention.

FIG. 14 is a perspective view of a magnet apparatus insert in accordancewith one embodiment of a present invention.

FIG. 15 is a side view of the magnet apparatus insert illustrated inFIG. 14.

FIG. 16 is a partial section view of a modified cochlear implantincluding the magnet apparatus insert illustrated in FIG. 14.

FIG. 17 is a perspective view of a magnet apparatus insert in accordancewith one embodiment of a present invention.

FIG. 18 is a side view of the magnet apparatus insert illustrated inFIG. 17.

FIG. 19 is a perspective view of a magnet apparatus insert in accordancewith one embodiment of a present invention.

FIG. 20 is a side view of the magnet apparatus insert illustrated inFIG. 19.

FIG. 21 is a top view of a portion of a modified cochlear implantincluding the magnet apparatus insert illustrated in FIG. 19.

FIG. 22 is a perspective view of a magnet apparatus insert in accordancewith one embodiment of a present invention.

FIG. 23 is a side view of the magnet apparatus insert illustrated inFIG. 22.

FIG. 24 is a top view of the magnet apparatus insert illustrated in FIG.22.

FIG. 25 is a perspective view of a magnet apparatus insert in accordancewith one embodiment of a present invention.

FIG. 26 is a side view of the magnet apparatus insert illustrated inFIG. 25.

FIG. 27A is a side view of the magnet apparatus insert illustrated inFIG. 25 with the flap bent.

FIG. 27B is a top view of a portion of a modified cochlear implantincluding the magnet apparatus insert illustrated in FIG. 25.

FIG. 28 is a perspective view of an implant magnet apparatus inaccordance with one embodiment of a present invention.

FIG. 29 is a perspective view of a portion of the implant magnetapparatus illustrated in FIG. 28.

FIG. 30 is an exploded view of the implant magnet apparatus illustratedin FIG. 28.

FIG. 31 is a plan view of a portion of the implant magnet apparatusillustrated in FIG. 28.

FIG. 32 is a section view take along line 32-32 in FIG. 28.

FIG. 33 is a section view similar to FIG. 32 with the implant magnetapparatus in an MRI magnetic field.

FIG. 34 is a perspective view of an implant magnet apparatus inaccordance with one embodiment of a present invention.

FIG. 35 is a section view take along line 35-35 in FIG. 34.

FIG. 36 is a perspective view of a magnet apparatus insert in accordancewith one embodiment of a present invention.

FIG. 37 is a side view of the magnet apparatus insert illustrated inFIG. 36.

FIG. 38 is a section view taken along line 38-38 in FIG. 37.

FIG. 39 is a perspective view of a portion of the magnet apparatusinsert illustrated in FIG. 36.

FIG. 40 is a section view of a portion of the magnet apparatus insertillustrated in FIG. 36.

FIG. 41 is a perspective view of an aspect of a cochlear implantmodification process in accordance with one embodiment of a presentinvention.

FIG. 42 is a partial section view of a modified cochlear implantincluding the magnet apparatus insert illustrated in FIG. 36.

FIG. 43 is a side view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 44 is a side, partial section view of a modified cochlear implantin accordance with one embodiment of a present invention.

FIG. 45 is a perspective view of a modified cochlear implant inaccordance with one embodiment of a present invention.

FIG. 46 is a perspective view of a magnet apparatus in accordance withone embodiment of a present invention.

FIG. 47 is a perspective view of a portion of the magnet apparatusillustrated in FIG. 46.

FIG. 48 is a perspective view of a portion of the magnet apparatusillustrated in FIG. 46.

FIG. 49 is an exploded perspective view of the magnet apparatusillustrated in FIG. 46.

FIG. 50 is a perspective view of a portion of the magnet apparatusillustrated in FIG. 46.

FIG. 51 is a perspective view of a portion of the magnet apparatusillustrated in FIG. 46.

FIG. 52 is a top view of a portion of the magnet apparatus illustratedin FIG. 46.

FIG. 53 is a section view of a portion of a magnet apparatus inaccordance with one embodiment of a present invention.

FIG. 54 is a section view of a portion of a magnet apparatus inaccordance with one embodiment of a present invention.

FIG. 55 is a partial section view of a cochlear implant and headpiece inaccordance with one embodiment of a present invention.

FIG. 56 is a section view similar to FIG. 55 with the cochlear implantin an MRI magnetic field.

FIG. 57 is a side view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 58 is a side, partial section view of a modified cochlear implantin accordance with one embodiment of a present invention.

FIG. 59 is a perspective view of a modified cochlear implant inaccordance with one embodiment of a present invention.

FIG. 60 is an exploded perspective view of a magnet apparatus inaccordance with one embodiment of a present invention.

FIG. 61 is a top view of a portion of the magnet apparatus illustratedin FIG. 60.

FIG. 62 is an exploded perspective view of the magnet apparatusillustrated in FIG. 60.

FIG. 63 is an exploded view of the magnet apparatus illustrated in FIG.60.

FIG. 64 is a partial section view of a cochlear implant and headpiece inaccordance with one embodiment of a present invention.

FIG. 65 is a partial section view similar to FIG. 64 with the cochlearimplant in an MRI magnetic field.

FIG. 66 is a perspective view of a magnet apparatus in accordance withone embodiment of a present invention.

FIG. 67 is a section view taken along line 67-67 in FIG. 66.

FIG. 68 is a perspective view of a magnet apparatus in accordance withone embodiment of a present invention.

FIG. 69 is a partial section view taken along line 69-69 in FIG. 68.

FIG. 70 is an exploded, partial section view of a magnet apparatus inaccordance with one embodiment of a present invention.

FIG. 71 is a perspective view of a magnet apparatus in accordance withone embodiment of a present invention.

FIG. 72 is a bottom view of the magnet apparatus illustrated in FIG. 71.

FIG. 73 is an exploded partial section view of an aspect of a cochlearimplant modification process in accordance with one embodiment of apresent invention.

FIG. 74 is a perspective view of a magnet apparatus in accordance withone embodiment of a present invention.

FIG. 75 is a perspective view of the magnet apparatus illustrated inFIG. 74.

FIG. 76 is a partial section view of a modified cochlear implant inaccordance with one embodiment of a present invention.

FIG. 77 is a top view of a magnet apparatus in accordance with oneembodiment of a present invention.

FIG. 78 is a perspective view of the magnet apparatus illustrated inFIG. 77.

FIG. 79 is a partial section view of a modified cochlear implant inaccordance with one embodiment of a present invention.

FIG. 80 is a perspective view of a magnet apparatus in accordance withone embodiment of a present invention.

FIG. 81 is a top view of the magnet apparatus illustrated in FIG. 80.

FIG. 82 is a side view of the magnet apparatus illustrated in FIG. 80.

FIG. 83 is a perspective view of a modified cochlear implant inaccordance with one embodiment of a present invention.

FIG. 84 is an exploded perspective view of a magnet apparatus inaccordance with one embodiment of a present invention.

FIG. 85 is an exploded partial section view of an aspect of a cochlearimplant modification process in accordance with one embodiment of apresent invention.

FIG. 86 is a top view of a modified cochlear implant in accordance withone embodiment of a present invention.

FIG. 87 is a perspective view of a magnet apparatus in accordance withone embodiment of a present invention.

FIG. 88 is a side view of the magnet apparatus illustrated in FIG. 87.

FIG. 89 is a section view of an aspect of a cochlear implantmodification process in accordance with one embodiment of a presentinvention.

FIG. 90 is a perspective view of an aspect of a cochlear implantmodification process in accordance with one embodiment of a presentinvention.

FIG. 91 is a perspective view of a modified cochlear implant inaccordance with one embodiment of a present invention.

FIG. 92 is a perspective view of a cochlear implant in accordance withone embodiment of a present invention.

FIG. 93 is a perspective view of the cochlear implant illustrated inFIG. 92.

FIG. 94 is a perspective view of a portion of the cochlear implantillustrated in FIG. 92.

FIG. 95 is a perspective view of a magnet apparatus in accordance withone embodiment of a present invention.

FIG. 96 is a side view of the magnet apparatus illustrated in FIG. 95.

FIG. 97 is a side view of a portion of the magnet apparatus illustratedin FIG. 95.

FIG. 98 is a perspective view of a magnet apparatus in accordance withone embodiment of a present invention.

FIG. 99 is a side view of the magnet apparatus illustrated in FIG. 98.

FIG. 100 is a side view of a portion of the magnet apparatus illustratedin FIG. 98.

FIG. 101 is a perspective view of a cochlear implant in accordance withone embodiment of a present invention.

FIG. 102 is a perspective view of a portion of the cochlear implantillustrated in FIG. 101.

FIG. 103 is a perspective view of a portion of the cochlear implantillustrated in FIG. 101.

FIG. 104 is a perspective view of a stencil in accordance with oneembodiment of a present invention.

FIG. 105 is a top view of the stencil illustrated in FIG. 104.

FIG. 106 is a top view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 107 is a side view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 108 is a side view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 109 is a side view of a cutting tool positioner in accordance withone embodiment of a present invention.

FIG. 110 is a perspective view of a cutting tool positioner illustratedin FIG. 109.

FIG. 111 is a perspective view of a cutting tool positioner illustratedin FIG. 109.

FIG. 112 is a bottom view of a cutting tool positioner illustrated inFIG. 109.

FIG. 113 is a side, partial section view of an aspect of a cochlearimplant modification process in accordance with one embodiment of apresent invention.

FIG. 114 is a side view of a center punch in accordance with oneembodiment of a present invention.

FIG. 115 is a bottom view of the center punch illustrated in FIG. 114.

FIG. 116 is a side, partial section view of an aspect of a cochlearimplant modification process in accordance with one embodiment of apresent invention.

FIG. 117 is a side, partial section view of an aspect of a cochlearimplant modification process in accordance with one embodiment of apresent invention.

FIG. 118 is a side view of a portion of a center punch in accordancewith one embodiment of a present invention.

FIG. 119 is a section view of an aspect of a cochlear implantmodification process in accordance with one embodiment of a presentinvention.

FIG. 120 is a perspective view of a coring tool in accordance with oneembodiment of a present invention.

FIG. 121 is a perspective view of a portion of the coring toolillustrated in FIG. 120.

FIG. 122 is a bottom view of the coring tool illustrated in FIG. 120.

FIG. 123 is a top view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 124 is an exploded perspective view of a coring and magnet removaltool in accordance with one embodiment of a present invention.

FIG. 125 is an exploded perspective view of the coring and magnetremoval tool illustrated in FIG. 124.

FIG. 126 is a section view of the coring and magnet removal toolillustrated in FIG. 124.

FIG. 127 is a side view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 128 is a top view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 129 is a bottom view of an aspect of a cochlear implantmodification process in accordance with one embodiment of a presentinvention.

FIG. 130 is a side view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 130A is a section view of an aspect of a cochlear implantmodification process in accordance with one embodiment of a presentinvention.

FIG. 131 is a perspective view of an aspect of a cochlear implantmodification process in accordance with one embodiment of a presentinvention.

FIG. 132 is a perspective view of an aspect of a cochlear implantmodification process in accordance with one embodiment of a presentinvention.

FIG. 133 is a side view of a coring and magnet removal tool inaccordance with one embodiment of a present invention.

FIG. 134 is a top view of the coring and magnet removal tool illustratedin FIG. 133.

FIG. 135 is a perspective view of a portion of the coring and magnetremoval tool illustrated in FIG. 133.

FIG. 136 is a perspective view of a portion of the coring and magnetremoval tool illustrated in FIG. 133.

FIG. 137 is a side view of a coring and magnet removal tool inaccordance with one embodiment of a present invention.

FIG. 138 is a top view of the coring and magnet removal tool illustratedin FIG. 137.

FIG. 139 is a perspective view of a portion of the coring and magnetremoval tool illustrated in FIG. 137.

FIG. 140 is an exploded perspective view of a portion of the coring andmagnet removal tool illustrated in FIG. 137.

FIG. 141 is an exploded perspective view of a portion of the coring andmagnet removal tool illustrated in FIG. 137.

FIG. 142 is a perspective view of a coring and magnet removal tool inaccordance with one embodiment of a present invention.

FIG. 143 is an exploded perspective view of the coring and magnetremoval tool illustrated in FIG. 142.

FIG. 144 is an exploded perspective view of the coring and magnetremoval tool illustrated in FIG. 142.

FIG. 145 is a perspective view of a portion of the coring and magnetremoval tool illustrated in FIG. 142.

FIG. 146 is a perspective view of a portion of the coring and magnetremoval tool illustrated in FIG. 142.

FIG. 147 is a bottom view of a portion of the coring and magnet removaltool illustrated in FIG. 142.

FIG. 148 is a partially exploded view of the coring and magnet removaltool illustrated in FIG. 142 with the blade partially extended.

FIG. 149 is a side view of a coring and magnet removal tool inaccordance with one embodiment of a present invention.

FIG. 150 is a perspective view of a portion of the coring and magnetremoval tool illustrated in FIG. 149.

FIG. 151 is a side view of a portion of the coring and magnet removaltool illustrated in FIG. 149.

FIG. 152 is a side view of an aspect of a cochlear implant modificationprocess in accordance with one embodiment of a present invention.

FIG. 153 is a plan view of a cochlear implant kit in accordance with oneembodiment of a present invention.

FIG. 154 is a block diagram of a cochlear implant system in accordancewith one embodiment of a present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The following is a detailed description of the best presently knownmodes of carrying out the inventions. This description is not to betaken in a limiting sense, but is made merely for the purpose ofillustrating the general principles of the inventions.

The present inventions include various apparatus and methods thatfacilitate in situ replacement of conventional implant magnets withMRI-compatible magnet apparatus (or “magnet apparatus”). Some of themethods and apparatus may also involve anchoring of the magnet apparatusto bone. In at least some instances, the magnet will be removed in situfrom the cochlear implant, a portion of the implant housing will beremoved to accommodate the larger magnet apparatus, and the magnetapparatus will be added to the modified cochlear implant housing. Asused herein, a “larger” magnet apparatus is a magnet apparatus that islarger in one or more of diameter, perimeter, length, width andthickness than the magnet that has been removed. The magnet will also beremoved and replaced by the magnet apparatus without damaging theantenna. Additionally, in at least some instances, a MRI-compatiblemagnet apparatus will not be secured to the remainder of the cochlearimplant, thereby allowing the cochlear implant to be removed (ifnecessary) without disturbing the bone anchor.

One example of a conventional cochlear implant that may be modified inaccordance with the present inventions is the cochlear implant 10described above with reference to FIGS. 1-2. Access to the implantedcochlear implant 10 may be obtained, for example, making an incisionthat allows a skin flap over the cochlear implant and, in particular,over the antenna portion 26 of the housing 12, to be lifted. The magnet28 may be removed from the magnet pocket 30 by way of the magnetaperture 42 (FIG. 4) after the access has been obtained. A portion ofthe housing 12 may then be removed in order to increase the availablevolume, as compared to the magnet pocket 30, for the magnet apparatus.In at least some implementations, the removed portion of the housing 12may be located radially inward of the antenna 18, radially outward ofthe magnet pocket 30, and may extend through the both of the housing topwall 44 and the housing bottom wall 48 (which defines the bottom surfaceof the housing). As such, the magnet pocket 30 and aperture 42 will beremoved, as will portions the top wall 44, the bottom wall 48, and anannular section of housing material which extends around the magnetpocket. The partial housing 12′ illustrated in FIGS. 5 and 6 includes amodified antenna portion 26′ with an aperture 50 that extends completelythrough the housing and that is located radially inward of the antenna18. The aperture 50 may be cylindrical (as shown) or other shapes suchas, but not limited to, square, hexagonal, and triangular. The thicknessof the aperture 50 is equal to the thickness of the modified antennaportion 26′. Exemplary tools that may be used to form the aperture 50are described below with reference to FIGS. 104-152.

The exemplary magnet apparatus insert 60 a illustrated in FIGS. 7A and7B may be inserted into the aperture 50 of the partial housing 12′ toform a modified cochlear implant. The exemplary magnet apparatus insert60 a includes a housing portion replacement 100 and an MRI-compatiblemagnet apparatus 200 that is embedded within the housing portionreplacement. The housing portion replacement 100, which may be formedfrom the same material as the cochlear implant housing 12 (e.g., asilicone elastomer) and overmolded onto the magnet apparatus 200,includes a magnet housing 102 (e.g., a disk-shaped housing) with amagnet pocket 104 in which the magnet apparatus 200 is located. Theshape and size of magnet housing 102 (e.g., the diameter and thickness)is the same as, or essentially the same as, that of the aperture 50. Theexemplary magnet apparatus 200, which is discussed in greater detailbelow with reference to FIGS. 28-33, is larger than the removed magnet28.

The housing portion replacement 100 of the magnet apparatus insert 60 amay be secured to partial housing 12′ with, for example, adhesiveapplied to the perimeter of the housing portion replacement to form themodified cochlear implant 10 a illustrated in FIG. 8. The modifiedcochlear implant 10 a includes a housing 12 a, which consists of thepartial housing 12′ and the housing portion replacement 100, as well asthe magnet apparatus 200 in place of the removed magnet 28. The antenna18 and other portions of the cochlear implant 10 (FIGS. 1 and 2) remainunchanged.

The cochlear implant 10 may be modified in other ways that alsofacilitate the replacement of the magnet 28 with an MRI-compatiblemagnet apparatus such as magnet apparatus 200. To that end, andreferring first to FIG. 9, the partial housing 12″ includes a modifiedantenna portion 26″ with an aperture 52 that extends partially throughthe housing and that is located radially inward of the antenna 18. Theaperture 52 may be cylindrical (as shown) or other shapes such as, butnot limited to, square, hexagonal, and triangular. The thickness of theaperture 50 is less the thickness of the modified antenna portion 26″and housing bottom wall 48 remains intact. Exemplary tools that may beused to form the aperture 50 a are described below with reference toFIGS. 36-49.

The exemplary magnet apparatus insert 60 b illustrated in FIG. 10 may beinserted into the aperture 52 of the partial housing 12″ to form amodified cochlear implant. The exemplary magnet apparatus insert 60 b issubstantially similar to insert 60 a and similar elements arerepresented by similar reference numerals. Here, however, the magnethousing 102 b of the housing portion replacement 100 b is somewhatthinner so as to conform to the thinner aperture 52. The magnet pocket104 and magnet apparatus 200 also extend to the bottom of the magnethousing 102 b.

The housing portion replacement 100 b of the magnet apparatus insert 60b may be secured to the partial housing 12″ with, for example, adhesiveto form the modified cochlear implant 10 b illustrated in FIG. 11. Theadhesive may be located on the bottom of the housing portion replacement100 b, in addition to the outer perimeter, in order provide additionalresistance to magnetic torque (FIG. 3). The modified cochlear implant 10b includes a housing 12 b, which consists of the partial housing 12″ andthe housing portion replacement 100 b, as well as the magnet apparatus200 in place of the removed magnet 28. The antenna 18 and other portionsof the cochlear implant 10 remain unchanged.

A cochlear implant, such as cochlear implant 10, may also be modified bysimply enlarging the magnet pocket in situ in order to accommodate anMRI-compatible magnet apparatus that is larger than the magnet 28.Referring to FIG. 12, housing material may be removed in such a mannerthat the modified housing 12 c includes a magnet pocket 30 c that islarger in diameter than the pre-modification magnet pocket 30 (shown indashed lines). The magnet apparatus 200 may then be inserted into themagnet pocket 30 c to form the modified cochlear implant 10 cillustrated in FIG. 13. Here too, the antenna 18 and other portions ofthe cochlear implant 10 remain unchanged. One example of a tool that maybe used to form the enlarged magnet pocket 30 c is described below withreference to FIGS. 120-123.

Another exemplary magnet apparatus insert 60 d is illustrated in FIGS.14 and 15. Magnet apparatus insert 60 d is substantially similar tomagnet apparatus insert 60 a and similar elements are represented bysimilar reference numerals. Here, however, a thin disk-shaped base 106is located under the magnet housing 102. The base 106 has a largerdiameter than the magnet housing 102 and, therefore, extends radiallybeyond the outer perimeter of the magnet housing. The base 106 mayintegral with the magnet housing 102, as shown, or may be a separateelement that is secured to the magnet housing.

The magnet apparatus insert 60 d may be added to, for example, theabove-described partial housing 12′ (FIGS. 5 and 6), which includes themodified antenna portion 26′ with the aperture 50. During insertion, themodified antenna portion 26′ may be bent away from the skull (and bentrelative to the remainder of the cochlear implant) so that the magnetapparatus insert 60 d can be positioned under the bottom wall 48 withthe magnet housing 102 aligned with the aperture 50. The modifiedantenna portion 26′ may then be pressed downwardly until the bottom wall48 rests on the base 106 in the manner illustrated in FIG. 16 tocomplete the modified cochlear implant 10 d. Adhesive may be used tosecure the magnet apparatus insert 60 d to the partial housing 12′. Theadhesive may be located on the top surface of the base 106, in additionto the outer perimeter of the magnet housing 102, in order provideadditional resistance to magnetic torque (FIG. 3). The antenna 18 andother portions of the cochlear implant 10 remain unchanged.

The exemplary magnet apparatus insert 60 e illustrated in FIGS. 17 and18 is substantially similar to magnet apparatus insert 60 d and similarelements are represented by similar reference numerals. Here, however,the base 106 includes an aperture 108 that allows the surgeon to securethe magnet apparatus insert 60 e to the skull with a bone screw 110 (orother bone anchor) to further resist magnetic torque. The modifiedcochlear implant may then be completed in the manner described abovewith reference to insert 60 d.

Another magnet apparatus insert that may be added to, for example, theabove-described partial housing 12′ (FIGS. 5 and 6) is the magnetapparatus insert generally represented by reference numeral 60 f inFIGS. 19 and 20. The magnet apparatus insert 60 f is similar to magnetapparatus insert 60 a and similar elements are represented by similarreference numerals. For example, the housing portion replacement 100 fincludes a magnet housing 102 f with a magnet pocket 104 in which themagnet apparatus 200 is located. The magnet housing 102 f is, however,longer than the magnet housing 102 and includes a plurality of flanges112 that extend radially from the longitudinal ends of the magnethousing.

During the addition of the magnet apparatus insert 60 f to the partialhousing 12′ (FIGS. 5-6), the modified antenna portion 26′ may be bentaway from the skull (and bent relative to the remainder of the cochlearimplant) so that the magnet apparatus insert 60 f can be positionedunder the bottom wall 48 with the magnet housing 102 f aligned with theaperture 50. The modified antenna portion 26′ may then be presseddownwardly until the bottom wall 48 rests on the lower set of flanges112. The upper set of flanges 112 may be pulled out of the aperture 50and positioned over the top wall 44, as shown in FIG. 21, to completethe modified cochlear implant 10 f. Adhesive may be used to secure themagnet apparatus insert 60 f to the partial housing 12′. In addition tothe outer perimeter of the magnet housing 102 f, the adhesive may belocated on the top surfaces of the lower flanges 12 and the bottomsurfaces of the upper flanges 12, the adhering the insert 60 f to thetop and bottom walls 44 and 48 of the partial housing 12′ as well as tothe material that defines the aperture 50. The antenna 18 and otherportions of the cochlear implant 10 remain unchanged.

Turning to FIGS. 22-24, the exemplary magnet apparatus insert 60 g issubstantially similar to magnet apparatus insert 60 f and similarelements are represented by similar reference numerals. To that end, themagnet apparatus insert 60 g includes a housing portion replacement 100g, with a magnet housing 102 g for the magnet pocket 104 and magnetapparatus 200, and a plurality of flanges 112 that extend radially fromone longitudinal end of the magnet housing. Here, however, a base 106 isassociated with the other longitudinal end instead of a second set offlanges 112. The magnet apparatus insert 60 g may be combined with, forexample, the partial housing 12′ in the manner described above to form amodified cochlear implant.

Another exemplary magnet apparatus insert is generally represented byreference numeral 60 h in FIGS. 25 and 26. Magnet apparatus insert 60 his substantially similar to magnet apparatus insert 60 d and similarelements are represented by similar reference numerals. Here, however,the base 106 h is slightly larger in diameter than base 106 and aflexible flap 114 extends from the base. More specifically, the flap 114has a base end 116 that is attached to (or is integral with) the base106 h and a free end 118.

The magnet apparatus insert 60 h may be combined with, for example, thepartial housing 12′ in the manner described above with reference to FIG.16 while the flap 114 is bent out of the way in, for example, the mannerillustrated in FIG. 27A. Adhesive located on the top surface of the base106 h, as well as the outer perimeter of the magnet housing 102, may beused to secure the magnet apparatus insert 60 h to the partial housing12′. The flap 114 may then be bent back and positioned over the housingtop wall 44 and the housing portion replacement 100 h, and securedthereto with adhesive, to complete the modified cochlear implant 10 hillustrated in FIG. 27B. Here too, the antenna 18 and other portions ofthe cochlear implant 10 remain unchanged.

Turning to FIGS. 28-32, the exemplary MRI-compatible magnet apparatus200 includes a case 202, with base 204 and a cover 206, a magnet frame208, and a plurality of elongate diametrically magnetized magnets 210within the frame that define a N-S direction. The exemplary case 202 isdisk-shaped and defines a central axis A1, which is also the centralaxis of the magnet frame 208. The magnet frame 208 is freely rotatablerelative to the case 202 about the central axis A1 over 360°. Themagnets 210 rotate with the magnet frame 208 about the central axis A1.Each magnet 210 is also freely rotatable relative to the magnet frame208 about its own longitudinal axis A2 over 360°. In the illustratedimplementation, the longitudinal axes A2 are parallel to one another andare perpendicular to the central axis A1. The axes A2 may benon-perpendicular to the central axis A1 in other implementations.

Given the ability of each magnet 210 to freely rotate about itslongitudinal axis A2, the magnets 210 align with one another in the N-Sdirection in the absence of a relatively strong external magnetic field(e.g., the MRI magnetic field discussed below with reference to FIG.33), and the at rest N-S orientation of the magnets 210 will beperpendicular to the central axis A1. So oriented, the magnetic fieldsof the diametrically magnetized magnets 210 are aligned with themagnetic field of a diametrically magnetized disk-shaped positioningmagnet, such as a headpiece magnet 510 (discussed below with referenceto FIG. 56). It should also be noted here that the magnetic field of thepositioning magnet will not be strong enough to cause the magnets 210 torotate out of the illustrated at rest N-S orientation. Although theframe 208 will rotate as necessary, the magnets 210 will remain in theN-S orientation illustrated in FIG. 32 and will continue to function asa magnetic unit in the presence of a headpiece magnet.

The exemplary case 202 is not limited to any particular configuration,size or shape. In the illustrated implementation, the case 202 is atwo-part structure that includes the base 204 and the cover 206 whichare secured to one another in such a manner that a hermetic seal isformed between the cover and the base. Suitable techniques for securingthe cover 206 to the base 204 include, for example, seam welding with alaser welder. With respect to materials, the case 202 may be formed frombiocompatible paramagnetic metals, such as titanium or titanium alloys,and/or biocompatible non-magnetic plastics such as polyether etherketone (PEEK), low-density polyethylene (LDPE), high-densitypolyethylene (HDPE), ultra-high-molecular-weight polyethylene (UHMWPE),polytetrafluoroethylene (PTFE) and polyamide. In particular, exemplarymetals include commercially pure titanium (e.g., Grade 2) and thetitanium alloy Ti-6Al-4V (Grade 5), while exemplary metal thicknessesmay range from 0.20 mm to 0.25 mm. With respect to size and shape, thecase 202 may have an overall size and shape similar to that ofconventional cochlear implant magnets, although such sizing/shaping isnot required because the magnet apparatus is not located within thecochlear implant housing 22.

Although the present inventions are not limited to any particularnumber, there are four elongate diametrically magnetized magnets 210 inthe exemplary magnet apparatus 200. Two of the otherwise identicalmagnets 210 are relatively long and two are relatively short in order toefficiently utilize the available volume within the case 202. Theexemplary magnets 210 are circular in a cross-section, have roundedcorners 212, and are located within low friction tubes 214. Suitablematerials for the magnets 210 include, but are not limited to,neodymium-boron-iron and samarium-cobalt.

The exemplary magnet frame 208 includes a disk 216 and a magnetreceptacle 218 that extends completely through the disk. The magnetreceptacle 218 is configured to hold all of the magnets 210 (four in theillustrated embodiment) and includes a relatively long portion and tworelatively short portions. Suitable materials for the frame 208, whichmay be formed by machining or injection molding, include paramagneticmetals, polymers and plastics such as those discussed above in thecontext of the case 202.

The inner surfaces of the case 202 and/or the surfaces of the frame 208may be coated with a lubricious layer. The lubricious layer may be inthe form of a specific finish of the surface that reduces friction, ascompared to an unfinished surface, or may be a coating of a lubriciousmaterial such as diamond-like carbon (DLC), titanium nitride (TiN),PTFE, polyethylene glycol (PEG), Parylene, fluorinated ethylenepropylene (FEP) and electroless nickel sold under the tradenames Nedox®and Nedox PF™. The DLC coating, for example, may be only 0.5 to 5microns thick. In those instances where the base 204 and a cover 206 areformed by stamping, the finishing process may occur prior to stamping.Micro-balls, biocompatible oils and lubricating powders may also beadded to the interior of the case to reduce friction. In the illustratedimplementation, the surfaces of the frame 208 may be coated with alubricious layer 220 (e.g., DLC), while the inner surfaces of the case202 do not include a lubricious layer. The lubricious layer 220 reducesfriction between the case 202 and frame 208, while the low frictiontubes 214 reduce friction between adjacent magnets 210 as well asbetween the case 202 and the magnets 210.

Turning to FIG. 33, when exposed to a dominant MRI magnetic field B, thetorque T on the magnets 210 will rotate the magnets about their axis A2,thereby aligning the magnetic fields of the magnets 210 with the MRImagnetic field B. The magnet frame 208 will also rotate about axis A1 asnecessary to align the magnetic fields of the magnets 210 with the MRImagnetic field B. When the magnet apparatus 200 is removed from the MRImagnetic field B, the magnetic attraction between the magnets 210 willcause the magnets to rotate about axis A2 back to the orientationillustrated in FIG. 32, where they are aligned with one another in theN-S direction and the N-S orientation of the magnets is perpendicular tothe central axis A1 of the case 202.

Additional information concerning magnet apparatus 200 and other similarMRI-compatible magnet apparatus may be found in PCT Pat. Pub. No.2017/105604, which is incorporated herein by reference in its entirety.

Another exemplary MRI-compatible magnet apparatus is generallyrepresented by reference numeral 200 a in FIGS. 34 and 35. The magnetapparatus 200 a includes a case 202, with base 204 and a cover 206, andmagnetic material particles (or “particles”) 223 within the internalvolume of a case 202. The particles 223 are in contact with one anotherand are independently and freely rotatable and otherwise movablerelative to one another and to the case. The particles 223 are free tomove from one X-Y-Z coordinate to another and/or rotate in anydirection. For example, some particles 223 may move linearly and/orrotate relative to other particles and relative to the case 202, whilethe orientation of the case remains the same, when the magnet apparatus200 a is exposed to an external magnetic field. Although the presentmagnetic material particles are not limited to any particular shape, theexemplary magnetic material particles 223 may be spherical or may benon-spherical, polyhedral shapes or at least substantially polyhedralshapes, i.e., multi-sided shapes that are regular or irregular,symmetric or asymmetric, with or without smooth side surfaces, and withor without straight edges, that will permit the particles to rotaterelative to one another when loosely packed. Any three-dimensionalshapes that permit the movement described above may also be employed.The magnetic material particles 223 may be formed from any suitablemagnetic material. Such materials include, but are not limited to,neodymium-iron-boron (“Nd₂Fe₁₄B”) magnetic material, isotropicneodymium, anisotropic neodymium, samarium-cobalt (“Sm₂Co₁₇”).Additional information concerning magnet apparatus 200 a and othersimilar MRI-compatible magnet apparatus may be found in PCT Pat. Pub.No. WO2016/190886, which is incorporated herein by reference in itsentirety.

Another exemplary MRI-compatible magnet apparatus is generallyrepresented by reference numeral 200 b in FIGS. 36-38. The magnetapparatus 200 b is similar to magnet apparatus 200 and similar elementare represented by similar reference numerals. For example, the magnetapparatus 200 b includes a case 202 b, with base 204 b and a cover 206b, a magnet frame 208, and a plurality of elongate diametricallymagnetized magnets 210. The case 202 b is also disk-shaped and defines acentral axis A1, while each of the magnets 210 is freely rotatablerelative to the magnet frame 208 about its own longitudinal axis, as isdiscussed above with reference to FIG. 29. The longitudinal axes of themagnets are parallel to one another and may be perpendicular to thecentral axis A1 (as shown), or non-perpendicular to the central axis A1.Here, however, the magnet apparatus 200 b may be used to form a modifiedcochlear implant without the use of a housing replacement portion.

The exemplary magnet apparatus 200 b includes, in addition to theelements described above, a thin disk-shaped apparatus base 211 with aflat bottom surface 213 that defines the bottom surface of the magnetapparatus. The apparatus base 211 has a larger diameter than the case202 b and, therefore, forms a flange that extends radially beyond theouter perimeter of the case. As such, a portion of the apparatus base211 forms a flange that extends radially beyond the case 202 b and maybe used to fix the position of the magnet apparatus 200 b relative tothe associated cochlear implant housing, as is discussed below withreference to FIG. 42.

Turning to FIGS. 39 and 40, the case 202 b in the exemplary magnetapparatus 200 b may be oriented relative to the apparatus base 211 insuch a manner that it is non-parallel to the flat bottom surface 213 (asshown) or in such a manner that it is parallel to the flat bottomsurface. In the illustrated implementation, the bottom inner surface 215(i.e. the surface closest to the apparatus base 211) of the case 202 bis offset from parallel to the flat bottom surface 213 by an angle θ ofabout 1.0 to 5.0 degrees, as is the top outer surface of the case (andmagnet apparatus), due to the presence of the angled wedge 217. Themagnets 110 also define a magnet plane MP that is offset from parallelto the flat bottom surface 213 by the same angle. The angular offset isespecially useful in those instance where the implant antenna portion 26b′ is slightly angled, as is discussed below with reference to FIG. 42.

In the illustrated implementation, the case base 204 b and the apparatusbase 211 together define an integral, one-piece unit. The case base 204b and the apparatus base 211 may be machined from a common blank ormetal injection molded in a common mold. In other implementations, aring formed from PEEK or a liquid-crystal polymer may be press fitted,clipped or overmolded onto the case base 204 b. Alternatively, a diskwith a wedge similar to that illustrated in FIG. 40 may be secured tothe bottom of the case base 204 b.

Turning to FIGS. 41 and 42, the exemplary magnet apparatus may be usedin conjunction with a partial housing 12 b′ formed from a cochlearimplant that is essentially identical to implant 10 (FIG. 4) but for theangle of the antenna portion 26 b′. The magnet apparatus 200 b may beinserted through the bottom of the aperture 50, i.e. the portion of theaperture that is closest to bone. The flange portion of the apparatusbase 211 that extends beyond the outer perimeter of the case 202 bengages the bottom wall 48, thereby fixing the position of the magnetapparatus 200 b relative to the partial housing 12 b′. The orientationof the magnet apparatus 200 b should also be such that the top surfacesof the implant antenna portion 26 b′ and the case 202 b slope in thesame direction. To that end, indicia 201 (FIG. 36) that identifies thelow end of the case 202 b may be provided on the top surface of the case202 b so that the surgeon can properly align the magnet apparatus 200 bwith the implant antenna portion 26 b′.

In some implementations, the top and side exterior surfaces of the case202 b may be enclosed in a thin PTFE shell, or coated with a lubriciousmaterial (such as Serene® coating from Surmodics Inc.), to facilitatepassage of the case 202 b into the aperture 50. The shell or coatingmaterials may also have anti-microbial properties, in some instances, toreduce the likelihood of biofilm formation and/or infection.

As alluded to above, in other implementations, a flange that extendsradially beyond the outer perimeter of the case may be employed inmagnet apparatus where the magnet case is parallel to the bottom surfaceof the flange. Here too, the flange may be used to fix the position ofthe magnet apparatus relative to the associated cochlear implanthousing.

Turning to FIGS. 43-45, another example of a magnet apparatus that maybe inserted into the aperture 50 of the partial housing 12′ to form amodified cochlear implant 10 c′ is the exemplary MRI-compatible magnetapparatus 200 c. The magnet apparatus 200 c may also be slightly largerthan the magnet pocket 30 and/or larger that the magnet 28 that was inthe pocket.

The magnet apparatus 200 c, which is described in greater detail belowwith reference to FIGS. 46-52, is substantially similar to magnetapparatus 200 and includes a disk-shaped case 202 c, with base 204 and acover 206 c (which is slightly thicker than cover 206), and a bone screw209 (or other bone anchor) that is permanently secured to the case base204, such as by welding. As used here, the phrase “permanently secured”means that, once connected, the bone screw will remain on the case 202 cunder normal use conditions, and cannot be removed from the case withoutdestruction of the bone screw, the case and/or the instrumentality thatsecures the two to one another. The size of the case 202 c (e.g., thediameter and the thickness) is slightly less that of the aperture 50. Inother implementations, the thickness of the case 202 c may be the sameas, or slightly greater than, the thickness of the aperture 50 and/orthe diameter of the case may be the same as the diameter of theaperture. Suitable materials for the case 202 c are described above.

After the magnet apparatus 200 c has been inserted into the aperture 50(FIG. 43), the magnet apparatus may be rotated to drive the bone screw209 into the bone (FIGS. 44 and 45). To that end, the case cover 206 cmay include a pair of circular indentations 207 or other structure(s)that may be engaged by a tool that is capable of rotating the magnetapparatus 200 c. One suitable tool is a torque limiting screwdriver,which will prevent damage to the magnet apparatus and/or bone that couldresult from the application of excessive torque. It should also be notedthat the magnet apparatus 200 c is not secured to the partial housing12′ or any other part of remainder of the modified cochlear implant 10c′. As such, some or all of the modified cochlear implant 10 c′ may beexplanted without disturbing the bone-anchored magnet apparatus 200 c.Turning to FIGS. 46-49, and in addition to the above-described case 202c and bone screw 209, the exemplary magnet apparatus 200 c includes amagnet frame 208 and a plurality of elongate diametrically magnetizedmagnets 210 within the frame that are cylindrical in shape and thatdefine a N-S direction. The exemplary case 202 c and bone screw 209define a central axis A1, which is also the central axis of the magnetframe 208, and the magnet frame is freely rotatable relative to the caseabout the central axis A1 over 360°. The magnets 210 rotate with themagnet frame 208 about the central axis A1. In other words, the bonescrew 209 defines the axis about which the magnet frame 208 and magnets210 rotate. Each magnet 210 is also freely rotatable relative to themagnet frame 208 about its own longitudinal axis A2 over 360°. In theillustrated implementation, the longitudinal axes A2 are parallel to oneanother and are perpendicular to the central axis A1. The axes A2 may benon-perpendicular to the central axis A1 in other implementations.

Given the ability of each magnet 210 to freely rotate about itslongitudinal axis A2, the magnets align with one another in the N-Sdirection in the absence of a relatively strong external magnetic field(e.g., the MRI magnetic field discussed below with reference to FIG.56), and the at rest N-S orientation of the magnets will beperpendicular to the central axis A1 (see FIG. 55). So oriented, themagnetic fields of the diametrically magnetized magnets 210 will bealigned with the magnetic field of a diametrically magnetizeddisk-shaped positioning magnet, such as the headpiece positioning magnetdiscussed below with reference to FIG. 55. It should also be noted herethat the magnetic field of the positioning magnet will not be strongenough to cause the magnets 210 to rotate out of the illustrated at restN-S orientation. Although the frame 208 will rotate as necessary due tothe magnetic field of the headpiece magnet, the magnets 210 will remainin the N-S orientation illustrated in FIG. 55 and will continue tofunction as a magnetic unit in the presence of a headpiece magnet.

The exemplary case 202 c is not limited to any particular configuration,size or shape. In the illustrated implementation, the case 202 c is atwo-part structure that includes the base 204 and the cover 206 c whichare secured to one another in such a manner that a hermetic seal isformed between the cover and the base. Suitable case materials andtechniques for securing the cover 206 c to the base 204 are describedabove. The exemplary metal thicknesses in this implementation may rangefrom 0.20 mm to 0.25 mm except for the circular portion of the cover 206c, which is slightly thicker (e.g., from 0.4 mm to 0.6 mm) toaccommodate the indentations 207. With respect to size, the diameter mayrange from 9 mm to 16 mm and the thickness may range from 1.5 mm to 4.0mm. The diameter of the case 202 c is 12.65 mm, and the thickness is3.35 mm, in the illustrated embodiment.

The exemplary bone screw 209 is about 2.5 to 4.0 mm in length and about1.5 to 2.5 mm in diameter. The length and diameter may, however, bealtered to suite particular skull thicknesses, such as those ofpediatric patients. Also, the present inventions are not limited to theillustrated bone screw and other types of bone anchors may be employed.By way of example, but not limitation, tri-start (or other multi-start)bone screws, bone screws with coatings or other features that promoteosseointegration, expandable bone anchors, and any other suitablecranial bone anchors may be secured to the case base 204 in place of theexemplary bone screw 209.

Turning to FIGS. 48-52, there are four elongate diametrically magnetizedmagnets 210 in the exemplary magnet apparatus 200 c. Two of theotherwise identical magnets 210 are relatively long and two arerelatively short in order to efficiently utilize the available volumewithin the case 202 c. As discussed above with reference to FIGS. 30-31,the exemplary magnets 210 are circular in a cross-section, have roundedcorners 212, and are located within low friction tubes 214. Theexemplary magnet frame 208 includes a disk 216 and a magnet receptacle218 that extends completely through the disk. The magnet receptacle 218is configured to hold all of the magnets 210 (four in the illustratedembodiment) and includes a relatively long portion and two relativelyshort portions. Suitable materials for the frame 208 and the magnets 210are discussed above. The inner surfaces of the case 202 c and/or thesurfaces of the frame 208 may be coated with lubricious layers 220 and221 (FIGS. 53 and 54), formed by the surfaces and materials discussedabove, to reduce friction.

Turning to FIG. 55, the modified cochlear implant 10 c′ may be used inconjunction with an external device such as a headpiece 800 (describedin greater detail below with reference to FIG. 153). The headpiece 800includes, among other things, a housing 802 and a diametricallymagnetized disk-shaped positioning magnet 810 that is not rotatablerelative to the housing. As noted above, the magnetic fields of thediametrically magnetized magnets 210 will align with the magnetic fieldof the headpiece magnet 810. The magnetic field of the headpiece magnet810 does not cause the magnets 210 to rotate out of their illustrated atrest N-S orientation, although the frame 208 will rotate as necessarydue to the magnetic field of the positioning magnet.

When exposed to a dominant MRI magnetic field B (FIG. 56), the torque Ton the magnets 210 will rotate the magnets about their axis A2, therebyaligning the magnetic fields of the magnets with the MRI magnetic fieldB. The magnet frame 208 will also rotate about axis A1 as necessary toalign the magnetic fields of the magnets 210 with the MRI magnetic fieldB. In other words, although the bone screw 209 will prevent the case 202c from moving, the freedom to rotate about axis A1 and axes A2 allowsthe magnets to move into alignment with the dominant magnetic field.When the magnet apparatus 200 c is removed from the MRI magnetic fieldB, the magnetic attraction between the magnets 210 will cause themagnets to rotate about their axis A2 back to the orientationillustrated in FIG. 55, where they are aligned with one another in theN-S direction and the N-S orientation of the magnets is perpendicular tothe central axis A1 of the case 202 c.

Another exemplary magnet apparatus is generally identified by referencenumeral 200 d in FIGS. 57-59. The magnet apparatus 200 d is similar tomagnet apparatus 200 c and similar elements are represented by similarreference numerals. For example, the exemplary magnet apparatus 200 dincludes a case 202 d, with a base 204 d and a cover 206 d, a bone screw209 d (or other anchor). The case 202 d may be formed from the samematerials as the case 202, and may have the same overall dimensions, insome embodiments. The magnet apparatus 200 d also includes the rotatableframe and rotatable magnets described below with reference to FIGS.60-63. The size of the case 202 d (e.g., the diameter and the thickness)is slightly less that of the aperture 50. In other implementations, thethickness of the case 202 d may be the same as, or slightly greaterthan, the thickness of the aperture 50 and/or the diameter of the casemay be the same as the diameter of the aperture.

Here, however, the bone screw 209 d is not secured to the case base 204d. The case 202 d and rotatable magnets are instead configured to permitpassage of the bone screw 209 d through the case. The case 202 d (andcomponents therein) may be inserted into the aperture 50, and the bonescrew 209 d may be inserted through the case (FIG. 57) before or afterthe case has been inserted into the aperture. The bone screw 209 d maythen be driven into the bone (FIGS. 58 and 59) until the head of thebone screw reaches a corresponding mating surface on the case 202 d,thereby anchoring the magnet apparatus 200 d to the skull and formingthe modified cochlear implant 10 d′. Here too, the magnet apparatus 200d is not secured to the partial housing 12′ or any other part ofremainder of the modified cochlear implant 10 d′.

Turning to FIGS. 60-63, the exemplary case 202 d includes a centralaperture 228 d that extends completely through the case to accommodatethe bone screw 209 d. The exemplary central aperture 228 d is acountersunk aperture that is defined by a central boss 230 d and atapered abutment 232 d. The central boss 230 d is part of the case base204 d and extends upwardly (in the illustrated orientation) from an endwall 234 d, while the tapered abutment 232 d is part of the case cover206 d and extends downwardly from an end wall 236 d to the central boss.The exemplary bone screw 209 d is a flat-head screw configured for usewith the countersunk central aperture 228 d.

The exemplary bone screw 209 d may be about 5.0 to 8.0 mm in length andabout 1.0 to 2.0 mm in diameter. The length and diameter may, however,be altered to suite particular skull thicknesses, such as those ofpediatric patients. Also, the present inventions are not limited to theillustrated bone screw and other types of bone anchors may be employed.By way of example, but not limitation, tri-start (or other multi-start)bone screws, bone screws with coatings or other features that promoteosseointegration, expandable bone anchors, and any other suitablecranial bone anchors may be inserted through the case 202 d in place ofthe exemplary bone screw 209 d.

In addition to the above-described case 202 d and bone screw 209 d, theexemplary magnet apparatus 200 d includes a magnet frame 208 and firstand second pluralities of elongate diametrically magnetized magnets 210and 210 d within the frame. The magnet frame 208 is freely rotatablerelative to the case 202 d over 360° about the central axis A1 definedby the case 202 d, the bone screw 209 d and the frame. The magnets 210and 210 d rotate with the magnet frame 208 about the central axis A1. Assuch, the bone screw 209 d defines the axis about which the magnet frame208 and magnets 210 and 210 d rotate. Each magnet 210 and 210 d is alsofreely rotatable relative to the magnet frame 208 about its ownlongitudinal axis A2 over 360°. In the illustrated implementation, thelongitudinal axes A2 are parallel to one another and are perpendicularto the central axis A1. The axes A2 may be non-perpendicular to thecentral axis A1 in other implementations. Given the ability of eachmagnet 210 and 210 d to freely rotate about its longitudinal axis A2,the magnets align with one another in the N-S direction in the absenceof a relatively strong external magnetic field and the at rest N-Sorientation of the magnets will be perpendicular to the central axis A1,as is shown in FIG. 64. The at rest orientation of the magnets 210 d isalso the result of the dominant magnetic fields of the larger magnets210. In at least some implementations, the diameter of the largermagnets 210 will be 50 to 55% greater than that of the magnets 210 d.

The magnets 210 and 210 d are each cylindrical and define a N-Sdirection. Like the magnets 210, the magnets 210 d have rounded corners212 d, and are located within low friction tubes 214 a. The lengths anddiameters of the magnets 210 and 210 d may be selected in a manner thatefficiently utilizes the available volume within the case 202 d giventhe presence of the central boss 230 d and tapered abutment 232 d. Tothat end, in the illustrated implementation, there are six otherwiseidentical magnets 210, two of which are relatively long and four ofwhich are relatively short. There are four identical magnets 210 d. Thelengths and diameters of the magnets 210 d are less than the lengths anddiameters of the magnets 210, which allows the magnets 210 d to fill ingaps within the internal volume of the case 202 d.

An alignment member 238 d may be used to ensure that the magnets 210 dremain in their illustrated locations with their axes A2 parallel to oneanother and to the axes A2 of the magnets 210. The exemplary alignmentmember 238 d, which is rotatable relative to the central boss 230 d, isblock-shaped and includes a central aperture 240 d for the central bossand side surfaces 242 d that abut adjacent magnets 210 and 210 d.Suitable materials for the alignment member 238 d include, but are notlimited to, PEEK and titanium. Turning to FIG. 64, the modified cochlearimplant 10 d′ may be used in conjunction with an external device such asaforementioned the headpiece 800 with the diametrically magnetizeddisk-shaped positioning magnet 810. The magnetic fields of thediametrically magnetized magnets 210 and 210 d are aligned with themagnetic field of a diametrically magnetized disk-shaped positioningmagnet 810. The magnetic field of the positioning magnet 810 does notcause the magnets 210 and 210 d to rotate out of their illustrated atrest N-S orientations, although the frame 208 will rotate as necessarydue to the magnetic field of the positioning magnet.

When exposed to a dominant MRI magnetic field B (FIG. 65), the torque Ton the magnets 210 and 210 d will rotate the magnets about their axisA2, thereby aligning the magnetic fields of the magnets with the MRImagnetic field B. The magnet frame 208 will also rotate about axis A1 asnecessary to align the magnetic fields of the magnets 210 and 210 d withthe MRI magnetic field B. Here too, although the bone screw 209 d willprevent the case 202 d from moving, the freedom to rotate about axis A1and axes A2 allows the magnets 210 and 210 d to move into alignment withthe dominant magnetic field. When the magnet apparatus 200 d is removedfrom the MRI magnetic field B, the magnetic attraction between themagnets 210 and 210 d, as well as the dominance of the magnetic field ofthe larger magnets 210, will cause each magnet to rotate about its axisA2 back to the orientation illustrated in FIG. 64, where they arealigned with one another in the N-S direction and the N-S orientation ofthe magnets is perpendicular to the central axis A1 of the case 202 d.

Another exemplary MRI-compatible magnet apparatus is generallyrepresented by reference numeral 200 e in FIGS. 66 and 67. The magnetapparatus 200 e includes the case 202 c, with the base 204 and a cover206 c, a bone screw 209 (or other bone anchor) that is permanentlysecured to the case base, and magnetic material particles (or“particles”) 223 within the internal volume of a case 202 c. Theparticles 223, which are described in greater detail above withreference to FIGS. 34 and 35, are in contact with one another and areindependently and freely rotatable and otherwise movable relative to oneanother and to the case.

The exemplary magnet apparatus 200 f illustrated in FIGS. 68 and 69includes a case 202 c, with a base 204 and a cover 206 c, a bone screw209 (or other bone anchor) that is permanently secured to the case base204, and a single diametrically magnetized disk-shaped magnet 210 f thatis rotatable within the case about axis A1. Unlike the MRI-compatiblemagnet apparatuses described above, the magnet 210 f is only rotatableabout a single axis. As such, the magnet apparatus 200 f should not bemisaligned with a MRI magnetic field by more than 30°.

The present inventors have also determined that some surgeons willprefer to remove a magnet apparatus prior to an MRI procedure, even inthose instances where the magnet apparatus is MRI-compatible, and thatit would be desirable to remove a bone anchored magnet apparatus and/orto replace a damaged magnet apparatus without drilling out the boneanchors. Accordingly, in still other implementations, the magnetapparatus may be configured in such a manner that the bone anchor willremain in the bone when the remainder of the magnet apparatus isremoved. One example of such a magnet apparatus is the magnet apparatus200 g illustrated in FIG. 70. The magnet apparatus 200 g is similar tomagnet apparatus 200 c and similar elements are represented by similarreference numerals. For example, the exemplary magnet apparatus 200 gincludes a case 202 c, with a base 204 and a cover 206 c, as well as themagnet frame 208 and plurality of elongate diametrically magnetizedmagnets 210 described above with reference to FIGS. 47-53.Alternatively, the magnet apparatus 200 g may include the magneticmaterial particles 223 described above with reference to FIGS. 34 and35, or the diametrically magnetized disk-shaped magnet 210 f describedabove with reference to FIGS. 68 and 69. The magnet apparatus 200 g alsoincludes a bone anchor. Here, however, the anchor 209 g is notpermanently secured to the case base 204, and is instead a separatestructural element that is attached to the bone independently of thecase 202 c. The anchor 209 g includes an anchor connector 246 g, and thecase 202 c is secured to the anchor by way of a corresponding caseconnector 248 g that is secured to the case. The anchor 209 g, oncedeployed, will be permanently connected to the bone, while theconnectors 246 g and 248 g form a releasable connection that will remainin place until removal of the case 202 c is required.

Although the present inventions are not to any particular connectors,the exemplary connectors 246 g and 248 g are threaded connectors. Othersuitable connectors include, but are not limited to, connectors thatinclude a detent and a spring-biased ball, and connectors that includestructures which may be rotated in and out of engagement with oneanother.

With respect to the manner in which the anchor 209 g is affixed to thebone, the anchor 209 g may include an outer bone engagement surface 250g. The bone engagement surface 250 g may threaded or otherwiseconfigured to screw into bone (including multi-start screw surfaces),may include coatings or other features that promote osseointegration,may be the outer surface of expandable anchor elements, or any othersuitable cranial bone anchoring instrumentality. Alternatively, theanchor may be of the type that is affixed to the bone with the StrykerSonicAnchor™ System, which is available from Stryker Trauma GmbH.

In still other implementations, a case and magnet arrangement similar to(or identical to) that described above with reference to FIGS. 57-63 maybe employed in conjunction with the bone anchor 209 g. A case connector(not shown) may be inserted through the aperture in the magnet apparatuscase and secured to the bone anchor connector. For example, a flat-headscrew configured for use with a countersunk aperture may be insertedthrough the aperture and secured to the bone anchor.

Another exemplary magnet apparatus is generally identified by referencenumeral 200 h in FIGS. 71-73. The magnet apparatus 200 h is similar tomagnet apparatus 200 and similar elements are represented by similarreference numerals. For example, the exemplary magnet apparatus 200 hincludes a case 202, with a base 204 and a cover 206, as well as therotatable frame 208 (not shown) and rotatable magnets 210 (not shown)described above. The case 202, rotatable frame 208 and magnets 210 maybe formed from the materials described above. Here, however, the magnetapparatus 200 h may be used to form a modified cochlear implant withoutthe use of a housing replacement portion. Instead, the magnet apparatus200 may be held in place through the use of bones screws in a mannersimilar to that described above with reference to FIGS. 43-70.

Referring more specifically to FIGS. 71 and 72, the magnet apparatus 200h also includes two or more protrusions 252 with apertures 254 that areeach configured to receive a bone screw 209′ (as shown) or other anchor.The protrusions 252 may extend radially or otherwise outwardly from thecase base 204 or some other portion of the case 202. The top of theprotrusions 252 may be countersunk, counterbored or flat depending onthe type of screw or other anchor with which it is intended to be used.The case 202 and protrusions 252 together define an integral, one-pieceunit. The case base 204 and the apertures 254 may be machined from acommon blank or metal injection molded in a common mold. In otherimplementations, the protrusions 252 may be separate elements that arewelded (e.g., laser welded) or otherwise secured to one another. In theillustrated implementation, the protrusions 252 are carried on a thindisk 256 that may also be welded to or otherwise secured to the bottomof the case base 204.

The bone screws 209′ may be inserted into apertures 254 before or afterthe magnet apparatus 200 h has been inserted into the aperture 50. Afterthe magnet apparatus 200 h has been inserted into the aperture 50, asshown in FIG. 73, the bone screws 209′ may be rotated to drive the bonescrews into the bone, thereby anchoring the magnet apparatus 200 h tothe skull and forming the modified cochlear implant 10 h′. Here too, themagnet apparatus 200 h is not secured to the partial housing 12′ or anyother part of remainder of the modified cochlear implant 10 h′.

Turning to FIGS. 74 and 75, the magnet apparatus 200 i illustratedtherein is substantially similar to magnet apparatus 200 h and similarelements are represented by similar reference numerals. For example, theexemplary magnet apparatus 200 i includes a case 202, with a base 204and a cover 206, as well as the rotatable frame 208 (not shown) androtatable magnets 210 (not shown) described above. Here, however, asingle protrusion 252 with an aperture 254 that is configured to receivea bone screw 209′ extends radially or otherwise outwardly from the case202 (e.g., from the base 204). The case 202 and protrusions 252 maytogether define an integral unit, or may be separate elements that aresecured to one another, as is described above.

Referring to FIG. 76, the bone screws 209′ may be rotated to drive thebone screw into the bone after the magnet apparatus 200 i has beeninserted into the aperture 50 to anchor the magnet apparatus 200 i tothe skull and form the modified cochlear implant 10 i. Like the magnetapparatus 200 h, the magnet apparatus 200 i is not secured to thepartial housing 12′ or any other part of remainder of the modifiedcochlear implant 10 i.

The respective overall shapes of the magnet apparatus 200 h and themagnet apparatus 200 i are such that, after the modified cochlearimplants 10 h′ and 10 i have been formed, portions of the aperture 50volume may remain open. There may be some instances where filling theentire volume is preferred. To that end, the exemplary magnet apparatusinsert 60 j illustrated in FIGS. 77 and 78, which may include a housingportion replacement 100 j and a magnet apparatus such as the magnetapparatus 200 h (as shown) or the magnet apparatus 200 i, is configuredto occupy the all of (or essentially all of) the aperture 50.

The exemplary housing portion replacement 100 j, which may be formedfrom the same material as the cochlear implant housing 12 (e.g., asilicone elastomer) and overmolded onto the magnet apparatus 200 h,includes a magnet housing 102 j (e.g., a disk-shaped housing) with amagnet pocket 104 j in which the magnet apparatus 200 h is located. Thehousing portion replacement 100 j also includes a pair of open regions106 i that are aligned with the protrusions 252. The open regions 106 ipermit passage of the bone screws 209′. The overall size and shape ofhousing portion replacement 100 j (e.g., the diameter and the thickness)is the same as, or essentially the same as, that of the aperture 50.Accordingly, the magnet apparatus insert 60 j fills the aperture 50 andallows the magnet apparatus 200 h to be anchored to bone as shown inFIG. 79.

In some implementations, the housing portion replacement 100 j (as wellas the other housing portion replacements disclosed herein) may beformed from a drug eluting silicone or foamed silicone that is mixedwith an antibacterial drug such as dexamethasone. The antibacterial drugeluting housing portion replacements will reduce the likelihood ofinfection, by resisting the growth of bacterial and biofilm, following asurgical procedure to replace a conventional magnet with aMRI-compatible magnet apparatus. In some instances, the drug elution maylast 6 months or more.

Other methods of anchoring a magnet apparatus to bone involve the use ofstiff straps that are secured to the top of the magnet apparatus andextend over the exterior of the cochlear implant housing antenna portionand down to the bone. One or more bone screws, or other anchors, may beused to secure the stiff straps and, therefore, the magnet apparatus andcochlear implant antenna portion to the bone.

One example of such a magnet apparatus is generally represented byreference numeral 200 k in FIGS. 80-82. The exemplary magnet apparatus200 k is similar to magnet apparatus 200 i and similar elements arerepresented by similar reference numerals. For example, the exemplarymagnet apparatus 200 k includes a case 202, with a base 204 and a cover206, as well as the rotatable frame 208 (not shown) and rotatablemagnets 210 (not shown) described above. The case 202, rotatable frame208 and magnets 210 may be formed from the materials described above.Here, however, the magnet apparatus 200 k includes a stiff strap 258.One end of the stiff strap 258 is secured to the case cover 206 and theother end includes an aperture 260 for a bone screw 209′ or other boneanchor. The shape of the stiff strap 258 corresponds to that of the topsurface of the housing antenna portion 26′. The stiffness of the strap258 may be sufficient to prevent movement of the magnet case 202.Suitable strap materials and manufacturing methods include, but are notlimited to, titanium (pressing or metal injection molding) and stiffbiocompatible polymers such as PEEK (molding).

The stiff strap 258 may be secured to the case 202 in any suitablefashion. In the illustrated implementation, where the strap is formedfrom titanium, the case 202 may be provided with a central boss 262 andthe stiff strap 258 may include a boss aperture 264 that extends throughthe thickened portion 266 of the strap. The stiff strap 258 may bewelded (e.g., laser welded) to the central boss 262. In those instanceswhere the stiff strap is formed from a polymer, the strap may include astructure (not shown) that can be press-fit over case to hold the strapin place.

Turning to FIG. 83, the case 202 of the exemplary magnet apparatus 200 kmay be inserted into the aperture 50 to form the modified cochlearimplant 10 k. The stiff strap 258 will then extend over the top surfacethe housing antenna portion 26′ in the illustrated location, or in otherlocations based on the angular/rotational orientation of the case 202relative to the aperture 50. The bone screw 209′ or other bone anchormay then be inserted through the aperture 260 and driven into bone tosecure the stiff strap 258 to the bone and, therefore, to secure themagnet apparatus 200 k, the cochlear implant antenna portion 26′, andthe modified cochlear implant 10 k to the bone.

Another exemplary magnet apparatus is generally represented by referencenumeral 200 l in FIGS. 84 and 85. The magnet apparatus 200 l issubstantially similar to magnet apparatus 200 k and similar elements arerepresented by similar reference numerals. For example, the magnetapparatus 200 l includes a case 202, with a base 204 and a cover 206, aswell as the rotatable frame 208 (not shown) and rotatable magnets 210(not shown) described above. The magnet apparatus 200 l also includes astiff strap 268 that may be anchored to bone and may be formed from thematerials and methods described above in the context of stiff strap 258.To that end, the exemplary case 202 includes a central boss 262 and thestiff strap includes a boss aperture 264.

Here, however, the stiff strap 268 extends in two directions from thecase 202 and includes an anchor aperture 260 at each end. As a result,the stiff strap 268 extends over two portions of the top surface thehousing antenna portion 26′ when the case 202 is inserted into theaperture 50 in the manner illustrated in FIG. 86. Bone screws 209′ orother bone anchors may then be inserted through the apertures 260 anddriven into bone at two points to secure the stiff strap 268 to the boneand, therefore, to secure the magnet apparatus 200 l, the cochlearimplant antenna portion 26′, and the modified cochlear implant 10 l tothe bone.

It should also be noted that although the stiff strap 268 is linear andanchored to the bone at locations that are offset from one another by180 degrees about the above-described axis defined by the case 202,other configurations may be employed such as, for example, V-shapes,L-shapes and X-shapes.

Turning to FIGS. 87 and 88, the exemplary magnet apparatus 200 millustrated therein is substantially similar to magnet apparatus 200 kand similar elements are represented by similar reference numerals. Forexample, the magnet apparatus 200 m includes a case 202, with a base 204and a cover 206, as well as the rotatable frame 208 (not shown) androtatable magnets 210 (not shown) described above. The magnet apparatus200 m also includes a stiff strap 270, with an aperture 260, that may beanchored to bone and may be formed from the materials described above inthe context of stiff strap 258.

Here, however, the magnet apparatus 200 m is configured in such a mannerthat the stiff strap 270 will extend under the bottom surface thehousing antenna portion 26′. To that end, the stiff strap 270 extendsradially or otherwise outwardly from the bottom end of the case base204. The case base 204 and stiff strap 270 may be machined from a commonblank or metal injection molded in a common mold, or may be separateelements that are welded (e.g., laser welded) or otherwise secured toone another.

Turning to FIGS. 89-91, the case 202 of the exemplary magnet apparatus200 m may be inserted into the bottom end of the aperture 50 of amodified antenna portion 12′ by, for example, bending the antennaportion 26′ upwardly. When the case 202 is fully inserted, the stiffstrap 270 will rest against the bottom wall 48, thereby completing themodified cochlear implant 10 m. A bone screw 209′ or other bone anchormay then be inserted through the aperture 260 and driven into bone tosecure the stiff strap 270 and, therefore, the magnet apparatus 200 m,to the bone.

Other cochlear implants may be pre-configured to include a magnetapparatus similar to that illustrated in FIGS. 87 and 88. For example,the exemplary cochlear implant 10 n illustrated in FIGS. 92 and 93 issubstantially similar to cochlear implant 10 and similar elements arerepresented by similar reference numerals. Here, however, the housing 12n includes a housing pocket 30 n that is accessible by way of a magnetaperture 42 n that extends through the housing bottom wall 48 n (FIG.94). The top wall 44 n does not include an aperture. The magnetapparatus 200 n is substantially similar to the magnet apparatus 200 min that it includes a case 202 n, with a base 204 and a cover 206 n, aswell as the rotatable frame 208 (not shown) and rotatable magnets 210(not shown) described above. The magnet apparatus 200 n also includes astiff strap 270, with an aperture 260, that may be anchored to bone. Thecase 202 n and strap 270 may be formed using the materials and methodsdescribed above.

In other embodiments, the number of stiff straps 270 and/or anchorpoints may be increased beyond the illustrated single strap. Forexample, an elongate strap that extends outwardly beyond the case 202 nin two areas that are offset from one another by 180 degrees about theabove-described axis defined by the case may be employed. Otherconfigurations where the straps define, for example, V-shapes, L-shapesand X-shapes, may also be employed.

The housing 12 n and magnet apparatus 200 n may also be configured insuch a manner that they mechanically interconnect with one another whenthe case 202 n is inserted through the aperture 42 n and into thehousing pocket 30 n. Referring to FIGS. 94-97, the case cover 206 n inthe illustrated implementation includes a relatively sharp projection272 and the housing 12 n includes a lip (or “undercut’) 274. Theprojection 272 snaps over the lip 274 as the case 202 n is inserted intothe housing pocket 30 n, thereby securing the magnet apparatus 200 n tothe housing 12 n and forming the cochlear implant 10 n. In otherimplementations, the case base 204 may include the projection, or thecase may include a recess and the housing pocket may include acorresponding projection. Regardless of the configuration of themechanical interconnect, the case 202 n can be pulled out of the housing12 n if desired because the housing material is relatively soft.

Turning to FIGS. 98-100, the exemplary magnet apparatus 200 oillustrated therein is substantially similar to magnet apparatus 200 nand similar elements are represented by similar reference numerals. Themagnet apparatus 200 o includes a case 202 o, with a base 204 and acover 206 o, as well as the rotatable frame 208 (not shown) androtatable magnets 210 (not shown) described above. The magnet apparatus200 o also includes one or more stiff straps 270, each with an aperture260, that may be anchored to bone. The case 202 o and strap 270 may beformed using the materials and methods described above. Here, however,the projection 272 o is not sharp and has a semi-circular shape. Themagnet apparatus 200 o may be used with a cochlear implant housing withor without a corresponding semi-circular indentation in the housingpocket.

One example of a cochlear implant that is pre-configured to include themagnet apparatus 200 m (FIGS. 87 and 88) is generally represented byreference numeral 10 p in FIG. 101. The cochlear implant 10 p includes,among other things, the above-described magnet apparatus 200 m and ahousing 12 p. The housing 12 p (FIGS. 102 and 103) is similar to housing12 n (FIGS. 92-94), but a lacks the lip 274 and has a magnet aperture 50p that extends completely through the antenna portion 26 p. Thisarrangement allows the housing 12 p to be thinner than, for example, thehousing 12 because there is no need for material above or below themagnet case 202.

It should be noted here that the present magnet apparatus inserts arenot limited to the MRI-compatible magnet apparatus described above orany other particular type of magnet apparatus. The magnet apparatusillustrated in U.S. Pat. No. 8,634,909, which has been proposed for usein an MRI magnetic field, is another example of a magnet apparatus thatmay be incorporated into the present magnet apparatus inserts.

As alluded to above, a wide variety of tools may be used to removematerial in situ from an implanted cochlear implant in the mannerdescribed above with reference to, for example, FIGS. 4-13. Examples ofsuch tools are described below in FIGS. 104-152. Such tools may beemployed in methods that involve removing the housing material (andmagnet) by forming incisions into the cochlear implant housing thatoriginate at the top surface (or “skin side”) of the implant as opposedto the bottom surface (or “bone side”). Access to the cochlear implantmay be obtained by way of an incision that is made directly over theantenna portion (including directly over the magnet) or by way of anincision that is in front of the antenna portion (i.e., to the left ofthe antenna portion in FIG. 2) and offset up to +/−30 degrees fromdirectly in front (i.e., from about reference numeral 42 to referencenumeral 46 in FIG. 1).

Referring first to FIGS. 104 and 105, the exemplary stencil 300 includesa main body 302 with an antenna portion 304 and a finger rest 306. Theantenna portion includes a cutout 308 with first and secondsemi-circular portions 310 that are separated by gaps 312. The cutout308 is sized and shaped to guide a scalpel blade 72 (FIG. 107) along acircular cutting path that is located radially inward of the antenna 18and radially outward of the magnet pocket 30. Suitable materials for thestencil include, but are not limited to, metals such as stainless steel.

Turning to FIGS. 106 and 107, the magnet 28 may remain within the pocket30 during a procedure involving the stencil 300 to create the modifiedantenna portion 26′ with the aperture 50 (FIGS. 5 and 6). Access to thecochlear implant may, in at least some instances, be provided by anincision that is directly over the antenna portion (including directlyover the magnet). The stencil 300 may be positioned over the cochlearimplant 10 (or other cochlear implant) in such a manner that the antennaportion 304 is located over the implant housing antenna portion 26 andis centered relative to the magnet 28 and magnet pocket 30. The positionof the stencil 300 relative to the cochlear implant 10 may be maintainedby applying downward pressure to the finger rest 306. The scalpel blade72 may then the inserted into one of the semi-circular cutout portions310, pressed completely or partially through the housing antenna portion26, and advanced from one end to the other. In those instances where theblade 72 is only pushed partially through the housing antenna portion26, the process will be repeated until a semi-circular cut is formedfrom top to bottom. Another semi-circular cut may also be formed withthe other cutout portion 310. With respect to the uncut regions underthe gaps 312, the stencil 300 may either be rotated slightly so that thecutout portions 310 will be aligned with the uncut regions or thestencil may be removed to expose the uncut portions. In either case, thescalpel blade 72 may then be pushed through the uncut regions to formthe severed portion 29 illustrated in FIG. 108. The stencil 300 may alsobe used to remove the severed portion 29 of the cochlear implant 10because the magnet 28, which remains in the pocket 30, will be attractedto the metal stencil.

The exemplary cutting tool positioner 320 illustrated in FIGS. 109-113may be used in conjunction with a sharp tool, such as a scalpel, to forman aperture 50 (FIGS. 5 and 6). The exemplary cutting tool positioner320 includes a centering post 322 and a rotatable tool guide 324 that ismounted on, and is rotatable to, the centering post. The exemplarycentering post 322 includes a handle 326, an axle 328 for the rotatabletool guide 324, and an anchor 330 that is configured to fit into themagnet pocket of the associated cochlear implant (e.g., the magnetpocket 30 of cochlear implant 10). The exemplary rotatable tool guide324, which rotates around the axis A3 defined by the centering post 322,is in the form of a disk 332 with a central aperture 334 for the axle328 and a slot 336 for the cutting tool blade. The distance D1 (FIG.112) from the slot 336 to the axis A results in the cutting tool bladebeing located radially inward of the antenna 18 and radially outward ofthe magnet pocket 30. Referring more specifically to FIG. 113, theexemplary cutting tool positioner 320 may be used in conjunction with ascalpel 70 that includes a blade 72 and a handle 74 to, for example,create the partial housing 12′ (FIGS. 5 and 6) that includes themodified antenna portion 26′ with the aperture 50. Access to thecochlear implant may, in at least some instances, be provided by anincision that is directly over the antenna portion 26 (and magnet 28).After the magnet 28 has been removed, the anchor 330 of the centeringpost 322 may be inserted into the magnet pocket 30, thereby performingthe function of centering the cutting tool positioner 320 relative tothe antenna 18 and magnet pocket 30. The rotatable tool guide 324 willrest on the top wall 44 if the cochlear implant housing 12. The scalpelblade 72 may then the inserted through the slot 336 and pressedcompletely or partially through the housing antenna portion 26. Therotatable tool guide 324 will keep the scalpel blade 72 on a circularpath as the blade is moved around the centering post 322 by the surgeon.In those instances where the blade 72 is only pushed partially throughthe housing antenna portion 26, more than one revolution will berequired for the cut to be formed from top to bottom. The centering post322, which is attached to the severed portion of the housing by way ofthe anchor 330, may be used to pull the severed portion out of thehousing to complete the above-described partial housing 12′ with themodified antenna portion 26′ (FIGS. 5 and 6).

Another tool that may be used to remove a portion of a cochlear implanthousing is the center punch 340 illustrated in FIGS. 114-116. Theexemplary center punch 340 includes a centering post 342 and a cutter344 that is mounted on the centering post in such a manner that thecutter may be moved longitudinally and rotationally. The exemplarycentering post 342 includes a handle 346 and an anchor 348 that isconfigured to fit into the magnet pocket of the associated cochlearimplant (e.g., the magnet pocket 30 of cochlear implant 10). Theexemplary cutter 344 includes a tubular member 350 with a blade 352 onone end and an annular flange 354 at the other end. The inner diameterof the blade 352 is greater than the diameter of the magnet pocket 30and is less than the diameter of the antenna 18 and, in the illustratedimplementation, is the same as the diameter of the aperture 50 (FIG. 5).

A variety of blades with ends having an overall circular may beemployed. The exemplary blade 352 illustrated in FIGS. 114-116 includesa tapered portion 356 and a continuous sharp circular edge 358. In otherimplementations of the tool, such as that illustrated in FIG. 118, theblade 352′ may include a plurality of spaced teeth 353.

Referring more specifically to FIG. 114, the exemplary center punch 340may be used to, for example, create the partial housing 12′ (FIGS. 5 and6) that includes the modified antenna portion 26′ with the aperture 50.Access to the cochlear implant may, in at least some instances, beprovided by an incision that is directly over the antenna portion 26(including directly over the magnet). After the magnet 28 has beenremoved, the anchor 348 of the centering post 342 may be inserted intothe magnet pocket 30, thereby performing the function of centering thecutter 344 (and cutter blade 352) relative to the antenna 18 and magnetpocket 30. The blade 352 may then be driven completely through thehousing antenna portion 26 by pressing on the flange 354 and driving thecutter 344 (and cutter blade 352) longitudinally along the centeringpost 342. The cutter 344 may also be rotated if necessary or desired.The centering post 342, which is attached to the severed portion of thehousing by way of the anchor 348, may be used to pull the severedportion 29 out of the housing (FIG. 117) to complete the above-describedpartial housing 12′ with a modified antenna portion 26′ (FIGS. 5 and 6).

The exemplary stencil 300, cutting tool positioner 320, and center punch340 may also be used in those instances where the surgeon intends toform an aperture that extends partially through the housing, such as thecylindrical aperture 52 illustrated in FIGS. 9 and 10. As illustratedfor example in FIG. 119, the cutting implement, e.g., the scalpel blade72 or cutter blade 352, will be pressed below the top wall 44 of thecochlear implant housing 12 to a depth equal to that of the magnetpocket 30. The circular cut 51 produced by the scalpel blade 72 orcutter blade 352 creates a substantially annular piece of housingmaterial 53 that surrounds the magnet pocket 30 and is connected to theremainder of the housing 12 at the bottom wall 48. The substantiallyannular piece of housing material 53 may then be cut, torn or otherwiseremoved from the housing 12 to form the aperture 52 illustrated in FIGS.9 and 10.

One example of a tool that may be used to enlarge a magnet pocket, e.g.,enlarge the magnet pocket 30 into the magnet pocket 30 a (FIG. 12), isthe coring tool 360 illustrated in FIGS. 120-122. Access to the cochlearimplant may, in at least some instances, be provided by an incision thatis directly over the antenna portion (including directly over themagnet). The coring tool 360 includes a handle 362 and a blade assembly364, with first and second blades 366 and 368 on a frame 370, which isconnected to the handle and performs the function of enlarging themagnet pocket by shaving shave material off of the housing 12 fromwithin the magnet pocket. The distance D2 between the free ends of theblades 366 and 368 is equal to the diameter of the enlarged magnetpocket. The frame 370 has an overall parallelepiped shape, with theblades 366 and 368 located at the acute angles, and includes a top wall372, a bottom wall 374 and side walls 376 and 378. The walls 372-378define openings 380 and 382 as well as an internal volume 384.

The exemplary tool 360 may be used to enlarge a magnet pocket in, forexample, the cochlear implant 10 in the manner illustrated in FIG. 123.After the magnet 28 has been removed (FIG. 4), the blade assembly 364may be inserted into the magnet pocket 30 by way of the magnet aperture42. The magnet pocket 30 will be stretched out if its circular shapebecause the distance D2 between the free ends of the blades 366 and 368is greater than the diameter of the magnet pocket 30. The handle 362 maythen be used to rotate the blade assembly 364 within the pocket 30. Suchrotation will cause the blades 366 and 368 to shave material off of thehousing 12 to create the modified housing 12 c, which includes a magnetpocket 30 c (FIG. 12) that is larger in diameter than thepre-modification magnet pocket 30. The shavings are free to enter orexit the volume 384 during rotation of the blade assembly 364 by way ofthe openings 380 and 382. The blade assembly 364 may then be removedfrom the pocket 30 c, and any shavings that remain may be removed bysuction. One example of a tool that may be used to remove the magnet anda portion of a cochlear implant housing is the coring and removal tool390 illustrated in FIGS. 124-126. The exemplary coring and removal tool390 includes a centering template 392 and a cutter 394 that is movablethrough the centering template. Access to the cochlear implant may, inat least some instances, be provided by an incision that is directlyover the antenna portion (including directly over the magnet). Theexemplary centering template 392 includes a base 396, a guide 398 with atapered inlet surface 400 and an aperture 402 that extends through thebase for the cutter 394, and an abutment 404 with a curved surface 406with a shape that corresponds to the outer edge of the associatedhousing antenna portion. The exemplary cutter 394 includes a tubularmember 408 with a blade 410 on one end and a connector 412 for a handle414 (FIG. 130) at the other end. Although a variety of blades with endshaving an overall circular shape may be employed, the exemplary blade410 includes a tapered portion 416 and a continuous sharp circular edge418. The cutter 394 may also be mounted on a screw punch, which willrotate the cutter, as is discussed below with reference to FIGS.149-153.

The respective positions of the aperture 402 and curved surface 406 ofthe exemplary centering template 392 are such that the aperture will becentered relative to the magnet 28 and magnet pocket 30 of theassociated cochlear implant 10 when the antenna portion 26 contacts thecurved abutment surface 406, as shown in FIGS. 127-129. The innerdiameter of the blade 410 is greater than the diameter of the magnetpocket 30 and is less than the diameter of the antenna 18 and, in theillustrated implementation, is the same as the diameter of the aperture50 (FIG. 5). Additionally, the outer diameter of the tubular member 408slightly less than the diameter of the template aperture 402, whichresults the blade 410 being centered relative to the magnet 28 andmagnet pocket 30.

Turning to FIGS. 130 and 130A, the exemplary coring and removal tool 390may be used to, for example, create the partial housing 12′ (FIGS. 5 and6) that includes the modified antenna portion 26′ with the aperture 50.After the centering template 392 has been positioned on top of thehousing antenna portion 26 and the curved surface of the abutment 404has been pressed against the end of the antenna portion, therebycentering the aperture 402 relative to the magnet 28, the tubular member408 of the cutter 394 may be inserted into the template guide 398 andthrough the aperture 402. The blade 410, which is also centered relativeto the magnet 28, may then be pushed through the antenna portion 12(between the magnet 28 and the antenna 18) until the circular edge 418passes through the bottom wall 48. The cutter 394 may also be rotated ifnecessary or desired. In addition to being severed from the remainder ofthe housing 12, the severed portion 29 (in which the magnet 28 islocated) will be wedged into the tapered portion 416 of the blade 410.The severed portion 29 (and magnet 28) may then be removed from thepartial housing 12′ with the blade 410, which as a modified antennaportion 26′ with the aperture 50, as can be seen in FIGS. 131 and 132.

Another tool that may be used to remove a portion of a cochlear implanthousing is the coring and removal tool 420 illustrated in FIGS. 133-136.The exemplary coring and removal tool 420 includes a centering template422, a cutter 424 that is movable relative to the centering template,and an actuator 426 that may be used to drive the cutter through acochlear implant antenna portion that is located on the centeringtemplate. The exemplary centering template 422 includes a base 428, aramp 430, an abutment 432 with a curved surface 434, and a relief 436for the cutter 424. The exemplary cutter 424 includes a blade 438 thathas a tapered portion 440 and a continuous sharp circular edge 442. Theexemplary actuator 426 includes first and second resilient (e.g., metal)elongate members 444 and 446 with first longitudinal ends that areconnected to one another at an attachment point 448. The secondlongitudinal ends, which are spaced apart from one another, support thecentering template 422 and the cutter 424. The exemplary actuator 426also includes a lever 450 that is connected to the first elongate member444 by a pin 452 that extends through an opening 454 in the secondelongate member 446. The lever 450 has a fulcrum 456 that is adjacent tothe pin 452 and that rests on the surface of the elongate member 446.

The exemplary actuator 426 functions in a manner similar to the actuatoron a finger nail clipper. Referring to FIG. 133, when the user appliesdownward force (in the illustrated orientation) to the lever 450, forcewill be applied to the second elongate member 446 by the fulcrum 456,thereby driving the cutter 424 towards the centering template 422. Theresilience of the elongate member 446 will cause the elongate member 446to return to the state illustrated in FIG. 133 when the force isremoved.

The respective positions of the cutter 424 and curved surface 434 of theexemplary centering template 422 are such that the cutter blade 438 willbe centered relative to the magnet 28 and magnet pocket 30 of theassociated cochlear implant 10 when the antenna portion 26 is pressedagainst the curved surface. The inner diameter of the blade 438 isgreater than the diameter of the magnet pocket 30 and is less than thediameter of the antenna 18 and, in the illustrated implementation, isthe same as the diameter of the aperture 50 (FIG. 5). Additionally, theouter diameter of the blade 438 is slightly less than the diameter ofthe template relief 436.

The exemplary coring and removal tool 420 illustrated in FIGS. 133-136may be used to, for example, create the partial housing 12′ (FIGS. 5 and6) that includes the modified antenna portion 26′ with the aperture 50.Access to the cochlear implant may, in at least some instances, beobtained by way of an incision that is in front of the antenna portionand offset up to +/−30 degrees from directly in front of the antennaportion. The low profile of the distal portion of the tool, i.e., theportion with the centering template 422 and the cutter 424, allows thedistal portion to be inserted under the skin by way of a relativelysmall incision. The ramp 430 facilitates sliding of the centeringtemplate 422 under the antenna portion of the in situ cochlear implant.The tool 420 can be moved toward the cochlear implant until the antennaportion is in contact with the curved surface 434, thereby centering theblade 438 relative to the magnet. The lever 450 may then be used todrive the cutter 424 downwardly until the circular edge 442 passescompletely through the antenna portion (between the magnet and theantenna) and the circular edge engages the surface of the relief 436. Insome instances, this will be about 6 mm of travel. The mechanicaladvantage associated with the fulcrum-based actuator 426 allows the userto drive the blade 438 through the housing with less than the 20-30 lbs.that would otherwise be required. The severed portion of the housing (inwhich the magnet is located) will be wedged into the tapered portion 440in the manner described above with reference to FIG. 130A. Releasing thelever 450 will allow the cutter to be returned to its rest position(FIG. 133), thereby pulling the severed portion (and magnet) out of thepartial housing.

The exemplary coring and removal tool 460 illustrated in FIGS. 137-141is similar to tool 420 (FIGS. 133-136) in that tool 460 includes acentering template 422, a cutter 424 that is movable relative to thecentering template, and an actuator 462 that may be used to drive thecutter through a cochlear implant antenna portion that is located on thecentering template. The centering template 422, which functions in themanner described above, includes a base 428, a ramp 430, a pair ofabutments 432′ with respective curved surfaces 434′, and a relief 436for the cutter 424. The exemplary cutter 424 includes a blade 438 with atapered portion 440 and a continuous sharp circular edge 442.

The exemplary actuator 462 includes a cutter carrier 464 that movesalong pins 466, an elongate member 468, a lever 470 and a gear assembly472 that converts motion of the lever into motion of the cutter carrier.The gear assembly 472 in the illustrated implementation includes a gear474 that is fixedly secured to the lever 470 and that rotates with thelever about a shaft 476, a rack gear 478 that is fixedly secured to thecutter carrier 464, and a pinion gear 480 that engages gears 474 and 478and that rotates about a shaft 482. The shafts 476 and 482 are mountedon shaft supports 484. Referring to FIGS. 137 and 139, when the usermoves the lever 470 downwardly (in the illustrated orientation), thegear assembly 472 will drive the cutter carrier 464 (and cutter 424)towards the centering template 422. Movement of the lever 470 in theopposite direction will drive the cutter carrier 464 (and cutter 424)away from the centering template 422.

The exemplary coring and removal tool 460 illustrated in FIGS. 137-141may be used to, for example, create the partial housing 12′ (FIGS. 5 and6) that includes the modified antenna portion 26′ with the aperture 50.Access to the cochlear implant may, in at least some instances, beobtained by way of an incision that is in front of the antenna portionand offset up to +/−30 degrees from directly in front of the antennaportion. The low profile of the distal portion of the tool, i.e., theportion with the centering template 422 and the cutter 424, allows thedistal portion to be inserted under the skin by way of a relativelysmall incision. The ramp 430 facilitates sliding of the centeringtemplate 422 under the antenna portion of the cochlear implant. The tool460 can be moved toward the cochlear implant until the antenna portionis in contact with the curved surfaces 434′, thereby centering the blade438 relative to the magnet. The lever 470 may then be used to drive thecutter 424 downwardly until the circular edge 442 passes completelythrough the antenna portion (between the magnet and the antenna) and thecircular edge engages the surface of the relief 436. In some instances,this will be about 6 mm of travel. The mechanical advantage associatedwith the gear-based actuator 462 allows the user to drive the blade 438through the housing with less than the 20-30 lbs. that would otherwisebe required. The severed portion of the housing (in which the magnet islocated) will be wedged into the tapered portion 440 in the mannerdescribed above with reference to FIG. 130A. Moving the lever 470 in theopposite direction will mover the cutter to the rest position (FIGS. 137and 139), thereby pulling the severed portion (and magnet) out of thepartial housing.

It should also be noted that the cutter 424 in the exemplary tool 460moves vertically, i.e. perpendicular to the template base and the bottomsurface of the housing antenna portion, which results in a preciselyformed aperture 50. The vertical movement also reduces the likelihood ofantenna damage.

Another tool that may be used to remove a portion of a cochlear implanthousing is the coring and removal tool 486 illustrated in FIGS. 142-148.The tool 486 includes a centering template 422 a, a cutter 424 a that ismovable relative to the centering template, and an actuator 488 that maybe used to drive the cutter through a cochlear implant antenna portionthat is located on the centering template. The centering template 422 aincludes a base 428 a, an abutment 432 with a curved surface 434, and arelief 436 for the cutter 424 a. The centering template 422 a alsoincludes a cutter guide 490 with an aperture 492. The exemplary cutter424 a includes a blade 438 that has a tapered portion 440 and acontinuous sharp circular edge 442 (note FIGS. 144-145).

The exemplary actuator 488 includes a rotatable cam 494, with acylindrical member 496 and diagonal slots 498, follower pins 500 thatextend outwardly from the cutter 424 a, and a pin guide 502, with a base504 and vertically extending members 506 with vertical slots 508 (i.e.,slots that extend in the direction of cutter movement). The cutter 424 ais located within the rotatable cam 494, and the follower pins 500extend through the diagonal cam slots 498 and into the vertical guideslots 508, as shown in FIGS. 146-147. The vertically extending members506 of the pin guide 502 are secured to the cutter guide 490. As aresult, the follower pins 500 will not rotate with the cam 494 and,instead, will move upwardly or downwardly in the diagonal slots 498 inresponse to rotational movement of the cam relative to the centeringtemplate 422 a and pin guide 502. The length of the diagonal slots 498may be such that the cutter 424 a will be in the fully retractedposition when the pins 500 are at the top end of the slots (FIGS. 142and 146) and the cutter 424 a will be in the fully extended position,with the blade 438 in contact with the surface of the relief 436, whenthe pins 500 are at the bottom end of the slots. The cutter 424 a isshown in a partially extended position in FIG. 148.

In the illustrated embodiment, the relative rotational movement isfacilitated by a lever 510, which is secured to the cam 494, and a lever512, which is secured to the centering template 422 a. The lever 510 maybe moved towards and away from the lever 512 to move the cutter down andup, while the lever 512 is held still so that the centering template 422a does not move relative to the associated cochlear implant.

The exemplary coring and removal tool 486 illustrated in FIGS. 142-148may be used to, for example, create the partial housing 12′ (FIGS. 5 and6) that includes the modified antenna portion 26′ with the aperture 50.Access to the cochlear implant may, in at least some instances, beobtained by way of an incision that is in front of the antenna portionand offset up to +/−30 degrees from directly in front of the antennaportion. The distal portion of the tool, i.e., the portion with thecentering template 422 a and the cutter 424 a, can be inserted under theskin by way of the incision until the centering template is under theantenna portion of the cochlear implant and the antenna portion is incontact with the curved surface 434. Such positioning will center theblade 438 relative to the magnet. The lever 510 may then be used todrive the cutter 424 a downwardly until the circular edge 442 passescompletely through the antenna portion (between the magnet and theantenna) and the circular edge engages the surface of the relief 436. Insome instances, this will be about 6 mm of travel. The mechanicaladvantage associated with the cam/follower actuator 488 allows the userto drive the blade 438 through the housing with less than the 20-30 lbs.that would otherwise be required. The severed portion of the housing (inwhich the magnet is located) will be wedged into the tapered portion 440in the manner described above with reference to FIG. 130A. Moving thelever 510 in the opposite direction will mover the cutter to theretracted position (FIG. 142), thereby pulling the severed portion (andmagnet) out of the partial housing.

It should also be noted that the cutter 424 a in the exemplary tool 486moves vertically, i.e. perpendicular to the template base and the bottomsurface of the housing antenna portion, which results in a preciselyformed aperture 50. The vertical movement also reduces the likelihood ofantenna damage.

One example of a tool that may be used to remove the magnet and aportion of a cochlear implant housing is the coring and removal tool 514illustrated in FIGS. 149-151. The exemplary coring and removal tool 514includes the centering template 392 and cutter 394 that are describedabove with reference to FIGS. 124-132, as well as a screw-punch actuator516 on which the cutter is fixedly mounted. The screw-punch actuator 516will rotate the cutter 394 as the cutter is pushed through the centeringtemplate 392 and cochlear implant antenna portion.

The exemplary screw-punch actuator 516 includes a handle 518 and a shaft520 that is both rotatable and longitudinally movable relative to thehandle. In particular, the shaft 518 includes a pair of spiral grooves522 and the handle includes a pair of fixed protuberances 524 that arerespectively located in one of the grooves. The protuberances 524 arecarried on the inner surface of a collar 526 whose rotation is preventedby the illustrated slot 528 and tab 530 arrangement in the illustratedimplementation. When the handle 518 is pushed downwardly, and the cutter394 is on an object that offers some resistance (e.g., a cochlearimplant housing), the shaft 520 will move into the handle and, due tothe presence of the spiral grooves 522 and protuberances 524, the shaftwill rotate. The cutter 394 will rotate with the shaft 520 until theshaft is fully inserted into the handle 518, as shown in FIG. 151.Rotation of cutter 394 reduces the amount of force necessary to cutthrough an object (as compared to an identical cutter that is notrotating). The amount of force necessary to drive the shaft 520 into thehandle 518, i.e., the amount of force that will be applied to the cutobject until the actuator reaches the state illustrated in FIG. 151, iscontrolled by a spring 530 that is located in a lumen 532 within thehandle.

Turning to FIG. 152, the exemplary coring and removal tool 514 may beused to, for example, create the partial housing 12′ (FIGS. 5 and 6)that includes the modified antenna portion 26′ with the aperture 50.Access to the cochlear implant may, in at least some instances, beprovided by an incision that is directly over the antenna portion(including directly over the magnet). After the centering template 392has been positioned on top of the housing antenna portion 26 and thecurved surface of the abutment 404 has been pressed against the end ofthe antenna portion, thereby centering the template aperture relative tothe magnet, the tubular member 408 of the cutter 394 may be insertedinto the template guide and through the template aperture. The blade 410(FIG. 150), which is also centered relative to the magnet, may then bepushed through the antenna portion 12 (between the magnet and theantenna) by applying axial force F to the handle 518. The shaft 520 andcutter 394 will rotate (note arrow R) as the shaft moves into handle 518and the cutter moves through the housing material. The magnitude of theaxial force F is controlled by the spring 530. The axial force F may beapplied until the circular edge 418 of the cutter blade passes throughthe bottom wall 48. As described above with reference to FIG. 130A, thesevered portion of the housing (in which the magnet is located) will bewedged into the tapered portion 416 of the blade 410 and can be easilyremoved.

It should also be noted here that the present methods of removingportions of cochlear implant housings are not limited to the toolsdescribed above. For example, lasers may be used to ablate portions of acochlear implant housing to facilitate removal of a portion thereof,such as the severed portion 29 (FIG. 107). Here, the stencil 300 (FIG.104) may be used as guide and to ensure that the antenna is not damagedby the laser.

Turning to FIG. 153, one example of a system (or “kit”) 80 in accordancewith at least one of the present inventions includes a magnet apparatusinsert with a MRI-compatible magnet apparatus, such as one of the magnetapparatus inserts 60 a (shown) or 60 b-60 h and 60 j, as well as a toolthat facilitates removal of a portion of a cochlear implant housing,such as the stencil 300 (shown), the cutting tool positioner 320, centerpunch 340 or the one of the coring and removal tools 390, 420, 460, 486and 514. Other kits may include the coring tool 360 and theMRI-compatible magnet apparatus 200. Still other kits may include a toolthat facilitates removal of a portion of a cochlear implant housing,such as the stencil 300 (shown), the cutting tool positioner 320, centerpunch 340, or the one of the coring and removal tools 390, 420, 460, 486and 514, in combination with MRI-compatible magnet apparatus such as anyof magnet apparatuses 200 b-200 p. Some kits may also include one ormore bone screws or other bone anchors and/or a screwdriver or othertool that may be used to drive the bone anchor into bone. The componentsof the kit 80 may be housed in a sterile package 82 that has a flatrigid bottom portion 84 and a top transparent top cover 86, therebyproviding a ready to use surgical kit. The bottom portion 84 may beformed from a material which allows the contents of the package to besterilized after being sealed within the package.

The present inventions have application in a wide variety of systemsincluding, but not limited to, those that provide sound (i.e., eithersound or a perception of sound) to the hearing impaired. One example ofsuch a system is an ICS system where an external sound processorcommunicates with a cochlear implant. Turning to FIG. 154, the exemplarycochlear implant system 90 includes the above-described modifiedcochlear implant 10 a, a sound processor, such as the illustrated bodyworn sound processor 700 or a behind-the-ear sound processor, and aheadpiece 800.

As noted above, the exemplary modified cochlear implant 10 a includes amodified flexible housing 12′, a processor assembly 14, a cochlear lead16 with an electrode array, an antenna 18, and an MRI-compatible magnetapparatus 200.

The exemplary body worn sound processor 700 includes a housing 702 inwhich and/or on which various components are supported. Such componentsmay include, but are not limited to, sound processor circuitry 704, aheadpiece port 706, an auxiliary device port 708 for an auxiliary devicesuch as a mobile phone or a music player, a control panel 710, one ormore microphones 712, and a power supply receptacle 714 for a removablebattery or other removable power supply 716 (e.g., rechargeable anddisposable batteries or other electrochemical cells). The soundprocessor circuitry 704 converts electrical signals from the microphone712 into stimulation data. The exemplary headpiece 800 includes ahousing 802 and various components, e.g., a RF connector 804, amicrophone 806, an antenna (or other transmitter) 808 and a disk-shapedpositioning magnet 810, that are carried by the housing. The headpiece800 may be connected to the sound processor headpiece port 706 by acable 812. The positioning magnet 810 is attracted to the magnetapparatus 200 of the cochlear stimulator 10 a, thereby aligning theantenna 808 with the antenna 18.

The stimulation data and, in many instances power, is supplied to theheadpiece 800. The headpiece 800 transcutaneously transmits thestimulation data, and in many instances power, to the cochlear implant10 a by way of a wireless link between the antennas. The stimulationprocessor 38 (FIG. 1) converts the stimulation data into stimulationsignals that stimulate the electrodes of the electrode array on thecochlear lead 16.

In at least some implementations, the cable 812 will be configured forforward telemetry and power signals at 49 MHz and back telemetry signalsat 10.7 MHz. It should be noted that, in other implementations,communication between a sound processor and a headpiece and/or auxiliarydevice may be accomplished through wireless communication techniques.Additionally, given the presence of the microphone(s) 712 on the soundprocessor 700, the microphone 806 may be also be omitted in someinstances. The functionality of the sound processor 700 and headpiece800 may also be combined into a single head wearable sound processor.Examples of head wearable sound processors are illustrated and describedin U.S. Pat. Nos. 8,811,643 and 8,983,102, which are incorporated hereinby reference in their entirety.

Although the inventions disclosed herein have been described in terms ofthe preferred embodiments above, numerous modifications and/or additionsto the above-described preferred embodiments would be readily apparentto one skilled in the art. By way of example, but not limitation, thepresent inventions may be used to simply replace the magnet within acochlear implant with a larger magnet (as opposed to a largerMRI-compatible magnet apparatus). inventions include any combination ofthe elements from the various species and embodiments disclosed in thespecification that are not already described. It is intended that thescope of the present inventions extend to all such modifications and/oradditions and that the scope of the present inventions is limited solelyby the claims set forth below.

1-31. (canceled)
 32. A magnet apparatus insert for use with a cochlearimplant, the cochlear implant including a housing with an antennaportion formed from a resilient elastomer, an antenna within the antennaportion, and an aperture within the antenna portion that extends atleast partially through the cochlear implant housing, the magnetapparatus insert comprising: a housing portion replacement having amagnet housing formed from a resilient elastomer and configured to fitwithin the aperture; and an MRI-compatible magnet apparatus embedded atleast partially within the magnet housing.
 33. A magnet apparatus insertas claimed in claim 32, wherein the magnet housing of the housingportion replacement defines an outer perimeter and first and secondlongitudinal ends; and the magnet apparatus insert further comprises adisk-shaped base associated with the first longitudinal end that extendsradially beyond the outer perimeter.
 34. A magnet apparatus insert asclaimed in claim 33, wherein the magnet apparatus insert furthercomprises a plurality of flanges that extend radially from the secondlongitudinal end of the magnet housing.
 35. A magnet apparatus insert asclaimed in claim 33, wherein the magnet apparatus insert furthercomprises a flap that extends from the base to a location over thesecond longitudinal end of the housing.
 36. A magnet apparatus insert asclaimed in claim 32, wherein the magnet housing of the housing portionreplacement defines first and second longitudinal ends; and the magnetapparatus insert further comprises a plurality of flanges that extendradially from at least one of the first and second longitudinal ends ofthe magnet housing.
 37. An apparatus as claimed in claim 36, wherein theMRI-compatible magnet apparatus includes a case and at least oneprotrusion, with an aperture that is configured to receive a bone screw,that extends outwardly from the case.
 38. A magnet apparatus as claimedin claim 32, wherein the MRI-compatible magnet apparatus comprises acase and at least one magnet within the case that is moveable relativeto the case.
 39. A magnet apparatus as claimed in claim 32, wherein theMRI-compatible magnet apparatus comprises a case and a plurality ofmagnetic material particles within the case that are moveable relativeto the case and to one another.
 40. A magnet apparatus as claimed inclaim 32, wherein the housing portion replacement comprises a drugeluting housing portion replacement. 41-59. (canceled)
 60. A method foruse with a cochlear implant in a patient, the cochlear implant includinga housing with an antenna portion formed from a resilient material andhaving a top side that faces skin and a bottom side that faces bone, anantenna within the antenna portion, a magnet pocket within the antennaportion, and a magnet within the magnet pocket, the method comprisingthe steps of: forming an incision in the skin; removing the magnet fromthe housing without removing the cochlear implant from the patient; andreplacing the magnet with an MRI-compatible magnet apparatus.
 61. Amethod as claimed in claim 60, wherein the step of forming an incisioncomprising forming an incision that is either directly over the antennaportion or in front of the antenna portion.
 62. A method as claimed inclaim 60, wherein the step of removing the magnet comprises removing aportion of the resilient material from the cochlear implant housingalong with the magnet; and the step of replacing the magnet with anMRI-compatible magnet apparatus comprises inserting an insert, includinga housing portion replacement and an MRI-compatible magnet apparatusthat is at least partially embedded within the housing portionreplacement, into the cochlear implant housing from which resilientmaterial has been removed.
 63. A method as claimed in claim 62, whereinthe housing portion replacement comprises a drug eluting housing portionreplacement. 64-82. (canceled)
 83. A magnet apparatus for use with animplantable medical device, the magnet apparatus comprising: a case; atleast one magnetic element within the case that is rotatable relative tothe case; and a bone anchor associated with the case that is configuredto anchor the case to bone.
 84. A magnet apparatus as claimed in claim83, wherein the bone anchor comprises a bone screw. 85-89. (canceled)90. A magnet apparatus as claimed in claim 83, wherein the case is atleast partially embedded within a housing portion replacement.
 91. Amagnet apparatus as claimed in claim 90, wherein the housing portionreplacement comprises a drug eluting housing portion replacement.
 92. Amagnet apparatus as claimed in claim 83, further comprising: a stiffstrap with an anchor aperture secured to the case. 93-94. (canceled) 95.A magnet apparatus as claimed in claim 83, further comprising the stepof a protrusion for mechanically interconnecting the case to a portionof the implantable medical device.
 96. A magnet apparatus as claimed inclaim 83, wherein the case defines a central axis; a magnet frame islocated within the case and rotatable relative to the case about thecentral axis; and the at least one magnetic element comprises aplurality of elongate diametrically magnetized magnets that are locatedin the magnet frame, the magnets defining a longitudinal axis and a N-Sdirection and being freely rotatable about the longitudinal axisrelative to the magnet frame. 97-102. (canceled)